2012 January 23 Monday
Low Birth Weight Triples Autism Risk

Why not a higher autism correlation between twins? birth weight is a key factor in determining autism risk.

EVANSTON --- Although the genetic basis of autism is now well established, a growing body of research also suggests that environmental factors may play a role in this serious developmental disorder affecting nearly one in 100 children. Using a unique study design, a new study suggests that low birth weight is an important environmental factor contributing to the risk of autism spectrum disorder (ASD).

“Our study of discordant twins -- twin pairs in which only one twin was affected by ASD -- found birth weight to be a very strong predictor of autism spectrum disorder,” said Northwestern University researcher Molly Losh. Losh, who teaches and conducts research in Northwestern’s School of Communication, is lead author of the study that will be published in the journal “Psychological Medicine” and is now available online.

But let me quibble about terminology: For millions of people on the autistic spectrum their autistic minds are not a disorder. Many are quite high functioning and happy to be on the autistic spectrum with the intellectual advantages they gain from their modes of thought. I think the problem is that too much cognitive variation has gotten subsumed under the autism label.

Still, this finding on birth weight is important.

The researchers found that lower birth weight more than tripled the risk for autism spectrum disorder in identical twin pairs in which one twin had ASD and the other did not.

My guess (and I expect this to become crystal clear in under 10 years due to cheap DNA sequencing technology) is that many genes that cause some aspects of autism were selected for. There was an adaptive advantage to a sort of specialization of cognitive labor. Genetic influences on a phenomenon that occurs a fairly high rate of incidence usually point to something that was selected for rather than developmental error or relatively rarer purely harmful genetic mutations. Highly maladaptive traits rarely get selected for.

There's some overlap between autism as a result of genes selected due to their reproductive advantages versus events that go wrong in brain development. That overlap has made clear thinking about autism harder to do. Given that clear thinking about the mind is hard to do in general that's not too surprising. But on the bright side, advances in psychometrics, neuroscience, and genetics are going to usher in a new age of understanding of the human mind and along with it will come a much more nuanced view of autism.

By Randall Parker    2012 January 23 10:39 PM   Entry Permalink | Comments (6)
2011 November 07 Monday
Separating Mom From Baby At Birth Stresses Infant?

Less quiet sleep and more brain activity when a baby is separated from its mother right after birth.

New York, November 2, 2011 -- A woman goes into labor, and gives birth. The newborn is swaddled and placed to sleep in a nearby bassinet, or taken to the hospital nursery so that the mother can rest. Despite this common practice, new research published in Biological Psychiatry provides new evidence that separating infants from their mothers is stressful to the baby.

It is standard practice in a hospital setting, particularly among Western cultures, to separate mothers and their newborns. Separation is also common for babies under medical distress or premature babies, who may be placed in an incubator. In addition, the American Academy of Pediatrics specifically recommends against co-sleeping with an infant, due to its association with Sudden Infant Death Syndrome, or SIDS.

Humans are the only mammals who practice such maternal-neonate separation, but its physiological impact on the baby has been unknown until now. Researchers measured heart rate variability in 2-day-old sleeping babies for one hour each during skin-to-skin contact with mother and alone in a cot next to mother's bed. Neonatal autonomic activity was 176% higher and quiet sleep 86% lower during maternal separation compared to skin-to-skin contact.

How many easily avoidable ways have we changed our environments that have increased our stress and made us less healthy?

By Randall Parker    2011 November 07 06:35 AM   Entry Permalink | Comments (7)
2010 November 30 Tuesday
Oxytocin Boosts Memories Of Mom

For better or worse oxytocin will intensify your feelings about Mom.

Researchers have found that the naturally-occurring hormone and neurotransmitter oxytocin intensifies men's memories of their mother's affections during childhood. The study was published today in Proceedings of the National Academy of Sciences.

Researchers at the Seaver Autism Center for Research and Treatment at Mount Sinai School of Medicine wanted to determine whether oxytocin, a hormone and neurotransmitter that is known to regulate attachment and social memory in animals, is also involved in human attachment memories. They conducted a randomized, double-blind, placebo-controlled, cross-over trial, giving 31 healthy adult men oxytocin or a placebo delivered nasally on two occasions. Prior to administering the drug/placebo, the researchers measured the men's attachment style. About 90 minutes after administering the oxytocin or the placebo the researchers assessed participants' recollection of their mother's care and closeness in childhood.

Either more caring or less caring memories were dredged up.

They found that men who were less anxious and more securely attached remembered their mothers as more caring and remembered being closer to their mothers in childhood when they received oxytocin, compared to when they received placebo. However, men who were more anxiously attached remembered their mothers as less caring and remembered being less close to their mothers in childhood when they received oxytocin, compared to when they received placebo. These results were not due to more general effects of oxytocin on mood or well-being.

So then is there a drug or hormone that'll intensify your feelings about high school? If so, any takers? I'd just as soon forget about it myself. But if I live long enough to get rejuvenation therapies then I'm looking forward to forming memories of my second childhood.

By Randall Parker    2010 November 30 09:51 PM   Entry Permalink | Comments (1)
2010 October 23 Saturday
New Moms Experience Mid-brain Growth

The gush of hormones in a new mother causes a spurt of brain growth.

WASHINGTON — Motherhood may actually cause the brain to grow, not turn it into mush, as some have claimed. Exploratory research published by the American Psychological Association found that the brains of new mothers bulked up in areas linked to motivation and behavior, and that mothers who gushed the most about their babies showed the greatest growth in key parts of the mid-brain.

Contra the press release, I do not think these results address the question of whether women perform at a lower intellectual level while pregnant. All the blood flowing to the fetus or hormones released during pregnancy might cause expectant mom to think fewer complex thoughts. I know women who feel like they got dumber during pregnancy and husbands who agree.

The scientists expected the hormones released after birth to cause brain changes.

Led by neuroscientist Pilyoung Kim, PhD, now with the National Institute of Mental Health, the authors speculated that hormonal changes right after birth, including increases in estrogen, oxytocin and prolactin, may help make mothers’ brains susceptible to reshaping in response to the baby. Their findings were published in the October issue of Behavioral Neuroscience.

The motivation to take care of a baby, and the hallmark traits of motherhood, might be less of an instinctive response and more of a result of active brain building, neuroscientists Craig Kinsley, PhD, and Elizabeth Meyer, PhD, wrote in a special commentary in the same journal issue.

Given the existing research literature these speculations were no great leap. For example, prolactin increases nerve myelin sheath production and repair. Prolactin also rises during pregnancy. So prolactin probably alters brain development during pregnancy as well. In rodents neuronal production increases during pregnancy and while raising pups. So these results from humans are not surprising.

Gray matter volume increased in new mothers in several areas of the brain.

The researchers performed baseline and follow-up high-resolution magnetic-resonance imaging on the brains of 19 women who gave birth at Yale-New Haven Hospital, 10 to boys and nine to girls. A comparison of images taken two to four weeks and three to four months after the women gave birth showed that gray matter volume increased by a small but significant amount in various parts of the brain. In adults, gray matter volume doesn’t ordinarily change over a few months without significant learning, brain injury or illness, or major environmental change.

The areas affected support maternal motivation (hypothalamus), reward and emotion processing (substantia nigra and amygdala), sensory integration (parietal lobe), and reasoning and judgment (prefrontal cortex).

Women most thrilled by their babies underwent the greatest brain remodeling.

In particular, the mothers who most enthusiastically rated their babies as special, beautiful, ideal, perfect and so on were significantly more likely to develop bigger mid-brains than the less awestruck mothers in key areas linked to maternal motivation, rewards and the regulation of emotions.

The emotional reactions and stimuli women receive from looking at, holding, and smelling their babies probably also contribute to the brain changes these researchers find. There could be a positive feedback loop between the hormone surges, sensory stimuli, emotional reactions, and brain changes.

These changes caused by becoming mothers likely cause permanent changes in brains. Longitudinal studies of women before any have children and then followed for decades could demonstrate whether this is the case. The change should be measurable using pictures and the sounds of babies combined with either MRI scans or to measure emotional responses.

Update: Another study finds oxytocin levels rise in both mom and dad after a baby shows up.

A fascinating new paper by Gordon and colleagues reports the first longitudinal data on oxytocin levels during the initiation of parenting in humans. They evaluated 160 first-time parents (80 couples) twice after the birth of their first child, at 6 weeks and 6 months, by measuring each parents' oxytocin levels and monitoring and coding their parenting behavior.

Three important findings emerged. At both time-points, fathers' oxytocin levels were not different from levels observed in mothers. Thus, although oxytocin release is stimulated by birth and lactation in mothers, it appears that other aspects of parenthood serve to stimulate oxytocin release in fathers.

Higher oxytocin is associated with more parenting behavior.

Finally, the findings revealed that oxytocin levels were associated with parent-specific styles of interaction. Oxytocin was higher in mothers who provided more affectionate parenting, such as more gazing at the infant, expression of positive affect, and affectionate touch. In fathers, oxytocin was increased with more stimulatory contact, encouragement of exploration, and direction of infant attention to objects.

"It is very interesting that elevations in the same hormone were associated with different types of parenting behaviors in mothers and fathers even though the levels of oxytocin within couples were somewhat correlated. These differences may reflect the impact of culture-specific role expectations, but they also may be indicative of distinct circuit effects of oxytocin in the male and female brain," commented Dr. John Krystal, Editor of Biological Psychiatry.

Yet another study found that oxytocin nasal spray increased trust. Oxytocin reduces fear. Parenting probably affects how parents emotionally react the rest of the world. Infant suckling boosts oxytocin release by nerve dendrites. So women who breast feed probably undergo more mental changes than women who bottle feed and therefore it seems reasonable to expect different parenting behavior between breast feeding and bottle feeding parents.

By Randall Parker    2010 October 23 05:51 PM   Entry Permalink | Comments (8)
2010 June 20 Sunday
Home Computers Lower School Performance?

At the risk of stating the obvious: technology isn't an unalloyed blessing. Technology sometimes creates problems while solving other problems. People sometimes respond to new technologies in ways that are harmful to self and others. With all that in mind: A big survey of kids in North Carolina found that home computers and high speed internet cut student test scores, especially among lower class kids.

DURHAM, N.C. -- Around the country and throughout the world, politicians and education activists have sought to eliminate the "digital divide" by guaranteeing universal access to home computers, and in some cases to high-speed Internet service.

However, according to a new study by scholars at Duke University's Sanford School of Public Policy, these efforts would actually widen the achievement gap in math and reading scores. Students in grades five through eight, particularly those from disadvantaged families, tend to post lower scores once these technologies arrive in their home.

Politicians and professional educators desperately want silver bullets that'll raise test scores, especially for lower scoring minorities. So they look for technologies that'll help. But the problem is that the streets find their own uses for technology. With access to the internet most people do not go searching for lectures on math and physics. Rather, porno, games, movies, music videos, chat, and other diversions are much more eagerly sought.

To make computers useful learning tools for kids the computers would need to have a really controlled set of learning applications and electronic books. The kids using these computers should have to earn access to fun diversions by doing productive learning work first. The learning applications might work better if some of them appeared as learning games. But even ideal computer software isn't going to do a lot to boost the performance of dumber kids or of kids that just don't have much natural curiosity.

What I'd like to know: If the kids were tested for IQ and exposure to computers is there an IQ level at which computer exposure raises performance? Or do computers distract kids of all IQ levels away from school work?

They collected data on 150,000 individuals. They stopped at 2005 in order to avoid the Facebook effect. You can bet that Facebook,Twitter, and the like are pulling kids even further away from books and school work.

"We cut off the study in 2005, so we weren't getting into the Facebook and Twitter generation," Vigdor said. "The technology was much more primitive than that. IM (instant messaging) software was popular then, and it's been one thing after the other since then. Adults may think of computer technology as a productivity tool first and foremost, but the average kid doesn't share that perception." Kids in the middle grades are mostly using computers to socialize and play games, Vigdor added, with clear gender divisions between those activities.

Computers are enabling both children and adults to create environments more closely suited to their desires and not always necessarily to the needs of their intellectual development.

Some evidence points to benefit from home libraries of plain old style books. Though the big collections of books in homes are also a proxy for smarter and more curious parents. Some of that smarts and curiosity is getting passed down to the kids thru genes. Again, studies are needed that control for IQ to measure whether the books in a home really make a big difference. Speaking as a child reading addict the benefit seems likely to be real. If I could go back in a time machine and change my childhood I'd give myself a much bigger and better collection of books to read.

By Randall Parker    2010 June 20 10:59 PM   Entry Permalink | Comments (16)
2010 June 02 Wednesday
Early And Late Puberty Makes Males Antisocial

Getting started into manhood too early or too late seems to cause more aggressive behavior.

Puberty that arrives earlier or later in adolescent boys relative to their peers can trigger chemicals that are related to antisocial behavior, according to researchers, whose findings have key implications for parents with aggressive boys.

"Aggressive behavior can begin very early, even in pre-school, and might be related to poor impulse control, difficulties in the family or just overall general problem behavior," said Elizabeth J. Susman, the Jean Phillips Shibley professor of biobehavioral health, Penn State. "We wanted to find out if earlier or later timing of puberty in adolescents has any biological factors related to it."

Susman and her colleagues looked at how the timing of puberty affects cortisol, a stress hormone, and salivary alpha amylase, an enzyme in saliva used as indicator of stress. Their findings appear in the May issue of Psychoneuroendocrinology.

But girls do not get turned into antisocial monsters by early or late puberty. (they've got other ways to become monsters)

The researchers found that lower levels of the alpha amylase in boys who experienced earlier maturity and higher levels of cortisol in boys who experienced later maturity are related to antisocial behavior. They found no similar correlation in girls.

I am not surprised by the results of early puberty. All pumped up with testosterone but with less than fully developed brains I'm not surprised they become more dangerous. But the older the kid the more developed the medial temporal lobe and other parts of the brain that help to exert control over beastly impulses. But the results from late puberty are surprising to me. Does a kid who enters puberty late also enter it more stressed to begin with? Or is the late arrival of hormones also too late to cause development of parts of the brain that control impulses?

Also see my post Adolescence Is Tough On The Brain.

By Randall Parker    2010 June 02 10:48 PM   Entry Permalink | Comments (2)
2010 March 16 Tuesday
Methamphetamine Harms Fetal Brains

No surprise here. Methamphetamine use during pregnancy harms fetal brains.

Washington, DC — Children whose mothers abused methamphetamine (meth) during pregnancy show brain abnormalities that may be more severe than that of children exposed to alcohol prenatally, according to a study in the March 17 issue of The Journal of Neuroscience. While researchers have long known that drug abuse during pregnancy can alter fetal brain development, this finding shows the potential impact of meth. Identifying vulnerable brain structures may help predict particular learning and behavioral problems in meth-exposed children.

"We know that alcohol exposure is toxic to the developing fetus and can result in lifelong brain, cognitive, and behavioral problems," said Elizabeth Sowell, PhD, of the University of California, Los Angeles, who led the research team. "In this study, we show that the effects of prenatal meth exposure, or the combination of meth and alcohol exposure, may actually be worse. Our findings stress the importance of drug abuse treatment for pregnant women," Sowell said. A structure called the caudate nucleus, which is important for learning and memory, motor control, and motivation, was one of the regions more reduced by meth than alcohol exposure.

Of the more than 16 million Americans over the age of 12 who have used meth, about 19,000 are pregnant women, according to data from the National Surveys on Drug Use and Health. About half of women who say they used meth during pregnancy also used alcohol, so isolating the effects of meth on the developing brain is difficult.

My advice: put alcoholic and meth using pregnant women in institutions where they get isolated from sources of alcohol and meth with frequent blood tests for drug and alcohol abuse. Women should not be allowed to damage the brains of their future babies.

By Randall Parker    2010 March 16 11:11 PM   Entry Permalink | Comments (5)
2009 October 10 Saturday
Some Babies Born To Be Anxious

Robin Marantz Henig has a lengthy article in New York Times Magazine about how some babies are born anxious and remain that way even as adults.

The tenuousness of modern life can make anyone feel overwrought. And in societal moments like the one we are in — thousands losing jobs and homes, our futures threatened by everything from diminishing retirement funds to global warming — it often feels as if ours is the Age of Anxiety. But some people, no matter how robust their stock portfolios or how healthy their children, are always mentally preparing for doom. They are just born worriers, their brains forever anticipating the dropping of some dreaded other shoe. For the past 20 years, Kagan and his colleagues have been following hundreds of such people, beginning in infancy, to see what happens to those who start out primed to fret. Now that these infants are young adults, the studies are yielding new information about the anxious brain.

These psychologists have put the assumptions about innate temperament on firmer footing, and they have also demonstrated that some of us, like Baby 19, are born anxious — or, more accurately, born predisposed to be anxious. Four significant long-term longitudinal studies are now under way: two at Harvard that Kagan initiated, two more at the University of Maryland under the direction of Nathan Fox, a former graduate student of Kagan’s. With slight variations, they all have reached similar conclusions: that babies differ according to inborn temperament; that 15 to 20 percent of them will react strongly to novel people or situations; and that strongly reactive babies are more likely to grow up to be anxious.

I'd love to see a political poll done where people are measured for their anxiety and then measured for their views on an assortment of political issues. Are anxious people more likely to support, say, socialized health care or measures against global warming or aggressive policies to stop terrorists or other measures that tend to reduce various risks? Which types of risks do they want to see action taken about at the political level?

I also wonder whether anxious people are more or less likely to become police, military officers, or politicians. Does the worry about threats cause them to seek power to take measures to reduce threats? Or do they try to avoid those sorts of jobs so that they can spend less time worrying?

The article reports that anxiety is the most common mental illness in America with 40 million suffers. Well, when state of mind that probably is genetically caused afflicts 13% of the population I have a hard time calling it an illness. It seems more like an evolutionary maladaptation in modern society. We evolved in niches where that higher level of hypervigilance and fear had selective value that enhanced survival. Now with TV news and web sites reporting all manner of dangers and bad outcomes people who have these anxiety-causing genes are suffering too much in response to the environment around them. Natural selection is obviously cruel.

The article reports that some people channel their reactive temperaments into conscientious and productive behavior. Not all suffer or live in constant worry. Higher IQ people are more likely to channel their higher reactivity into productive pursuits. I wonder whether it will be possible to make our innate traits more often useful and less often crippling.

I've argued with people who insist that Steven Pinker's book The Blank Slate: The Modern Denial of Human Nature attacks a straw man. Yet here's Harvard child psychologist Jerome Kagan explaining that it took him 20 years to take seriously the idea that he was seeing anxiety in children that was due to innate differences in temperaments.

Among these prose summaries, which ultimately Kagan and a colleague, Howard Moss, turned into the book “Birth to Maturity,” were descriptions indicating that babies had different innate temperaments. Kagan studiously ignored this finding; it didn’t fit with his left-leaning politics, which saw all individuals as born inherently the same — blank slates, to use the old terminology — and capable of achieving anything if afforded the right social, economic and educational opportunities. “I was so resistant to awarding biology much influence, I didn’t follow up on the inhibited temperaments I was seeing,” he told me. It took another 20 years of listening to arguments about nature versus nurture for Kagan finally to entertain the possibility that some behavior might be attributed to genes.

We live in the era when the genetic causes of all these innate differences are about to be discovered. The costs of DNA sequencing have fallen so far so fast that the flood gates of DNA sequencing data have opened and the rate of DNA sequenc is going to increase by a few more orders of magnitude. So neuroscientists are going to be able to run down and identify the many genetic influences on temperament and intelligence.

The genetic sequencing results aren't even needed to identify anxious children under the age of 1. The article reports that Jerome Kagan figured out that the amygdala plays a big role in anxiety in ways that also change heart beat, respiration, blood pressure and other externally measurable signs. So babies can be classified for anxious temperament pretty easily.

The whole article is worth reading in full.

By Randall Parker    2009 October 10 11:05 PM   Entry Permalink | Comments (0)
Flu Infection During Pregnancy Harmful To Fetal Brains

Pregnant women should seriously ponder whether to get to a doctor and get vaccinated for H1N1 flu and regular seasonal flu. Babies in the womb during the great 1918 flu pandemic suffered more brain development and other development problems.

Flu poses still more risks for the unborn. In April, it was reported that men who were in the womb in early 1970, when a mild flu pandemic hit Norway, had lower scores in army intelligence tests than normal. A 2006 study showed that babies in the womb in September 1918 went on to have lower incomes and education levels, and higher rates of disability. And babies whose mothers have ordinary flu in early pregnancy are 7 times as likely to develop schizophrenia.

That's not good.

A New York Times flu vaccine Q&A includes an item that perhaps suggests at least one reason why flu during pregnancy is especially problematic: pregnancy temporarily reduces lung capacity and so oxygen supply would be especially impacted by flu-caused lung congestion. That'd have harmful effects on fetal development.

A woman’s immune system is compromised during pregnancy. Late in the pregnancy, the fetus pushes up against the thoracic cage and decreases a woman’s lung capacity, putting her at risk for respiratory complications if she contracts flu. A New England Journal study found that pregnant women with swine flu were nine times more likely to be in intensive care.

Think you might get pregnant this winter or already pregnant? Think about flu shots.

By Randall Parker    2009 October 10 07:13 PM   Entry Permalink | Comments (5)
2009 October 08 Thursday
Licorice May Cause Lower IQ And AHDH In Fetuses

Hey expectant mom, cut out the licorice.

Expectant mothers who eat excessive quantities of liquorice during pregnancy could adversely affect their child's intelligence and behaviour, a study has shown.

A study of eight year old children whose mothers ate large amounts of liquorice when pregnant found they did not perform as well as other youngsters in cognitive tests.

They were also more likely to have poor attention spans and show disruptive behaviour such as ADHD (attention deficit hyperactivity disorder).

It is thought that a component in liquorice called glycyrrhizin may impair the placenta, allowing stress hormones to cross from the mother to the baby.

We need to know all the food constituents that cause harm to developing fetuses. Surely more are waiting to be discovered. The one I'm curious to know more about: high fructose. Our ancestors consumed about an order of magnitude less fructose. Could it be messing up fetal development?

By Randall Parker    2009 October 08 06:23 PM   Entry Permalink | Comments (7)
2009 August 25 Tuesday
More Developed Brain White Matter In Risk Taking Teens

Teenagers who take more risks have more adult-like brains as measured by white matter.

A new study using brain imaging to study teen behavior indicates that adolescents who engage in dangerous activities have frontal white matter tracts that are more adult in form than their more conservative peers.

The brain goes through a course of maturation during adolescence and does not reach its adult form until the mid-twenties. A long-standing theory of adolescent behavior has assumed that this delayed brain maturation is the cause of impulsive and dangerous decisions in adolescence. The new study, using a new form of brain imaging, calls into question this theory.

In order to better understand the relationship between high risk-taking and the brain's development, Emory University and Emory School of Medicine neuroscientists used a form of magnetic resonance imaging (MRI) called diffusion tensor imaging (DTI) to measure structural changes in white matter in the brain. The study's findings are published in the Aug. 26, 2009 PLoS ONE.

Why do you suppose that is? I'd like to know whether the teens whose white matter develops more quickly have more testosterone. Does testosterone speed brain development while also increasing risk-taking behavior?

By Randall Parker    2009 August 25 11:18 PM   Entry Permalink | Comments (2)
2009 July 21 Tuesday
Pollutants Lower Child IQ?

Pollution is bad.

A mother's exposure to urban air pollutants known as polycyclic aromatic hydrocarbons (PAHs) can adversely affect a child's intelligence quotient or IQ, a study reports. PAHs are chemicals released into the air from the burning of coal, diesel, oil and gas, or other organic substances such as tobacco. In urban areas motor vehicles are a major source of PAHs.

The study, funded by the National Institute of Environmental Health Sciences (NIEHS), a component of the National Institutes of Health, the U.S. Environmental Protection Agency and several private foundations, found that children exposed to high levels of PAHs in New York City had full scale and verbal IQ scores that were 4.31 and 4.67 points lower than those of less exposed children. High PAH levels were defined as above the median of 2.26 nanograms per cubic meter (ng/m3). A difference of four points, which was the average seen in this study, could be educationally meaningful in terms of school success, as reflected, for example, in standardized testing and other measures of academic performance. However, the researchers point out that the effects may vary among individual children.

But one can easily imagine smarter parents figuring out how to reduce their family's exposure to air pollutants. So this could be a selection effect.

But the subjects had common backgrounds and might not have differed all that much in other characteristics. Hard to tell.

The study was conducted by scientists from the Columbia University Center for Children's Environmental Health. It included children who were born to non-smoking black and Dominican-American women age 18 to 35 who resided in Washington Heights, Harlem or the South Bronx in New York. The children were followed from utero to 5 years of age. The mothers wore personal air monitors during pregnancy to measure exposure to PAHs and they responded to questionnaires.

Live in the country and breath cleaner air. If you have to live in a city or near a highway consider getting a HEPA filter in your residence.

By Randall Parker    2009 July 21 11:24 PM   Entry Permalink | Comments (3)
2009 July 15 Wednesday
Brain Area For Social Cognition Present By Age 6

By age 6 brain areas for modeling others have shown up and begun functioning.

Social cognition—the ability to think about the minds and mental states of others—is essential for human beings. In the last decade, a group of regions has been discovered in the human brain that are specifically used for social cognition. A new study in the July/August 2009 issue of the journal Child Development investigates these brain regions for the first time in human children. The study has implications for children with autism.

Researchers at Massachusetts Institute of Technology (MIT) and Yale University scanned the brains of 13 children ages 6 to 11 as they listened to children's stories. At the moment the plot of the stories revealed what a character wanted, believed, or knew, or presented the mental state of the character, the researchers observed increased activity in these specific brain regions. When the story turned to other topics—such as the physical world or the visual appearance of the characters—activity in these brain regions went back down.

Do people on the autistic spectrum have smaller brain areas dedicated to social cognition? Do adult Aspies have less brain area dedicated to reading others and modeling others? If so, do they have more brain area dedicated to path and reasoning?

By Randall Parker    2009 July 15 10:49 PM   Entry Permalink | Comments (2)
Brain Development Of Adolescent Girls Different Than Boys

Here's a big non-shocker: science shows once again that in adolescence girls become different than boys in how they think.

The study, by researchers at the National Institute of Mental Health (NIMH) and Georgia State University, appears in the July/August 2009 issue of the journal Child Development.

The researchers looked at mostly White psychiatrically healthy Americans ages 9 to 17 to determine what happens in the brains of preteens and teens at a time of significant change in social behavior. The youths looked at photos of peers and rated their interest in interacting with each one. Then they underwent a brain scan while reviewing the pictures and rated how much each young person in the picture might want to interact with them in return. The youths were told they would be matched with a peer for a chat after the scan.

The study found that in older girls (as compared to younger girls), brain regions (the nucleus accumbens, insula, hypothalamus, hippocampus, and amygdala) associated with social rewards and motivation, processing emotions, hormonal changes, and social memory responded differently when they thought about being judged by their peers, especially peers with whom they wanted to interact. These differences were not evident between younger and older boys.

What type of cognitive ability changes more in male adolescents? I would expect spatial reasoning to take a big leap in developing males.

The mind areas for thinking about other people are developing in preschoolers.

The study, in the July/August 2009 issue of the journal Child Development, was conducted by researchers at Queen's University at Kingston in Ontario, Canada.

In the preschool years, children develop social skills by learning how to understand others' thoughts and feelings, or their theory of mind. In most children, theory of mind changes over time so they come to understand that others' thoughts are representations of the world that may or may not match the way the world actually is. In their study of EEGs of 29 4-year-olds, the researchers found that these changes are related to the functional development of two parts of the brain—the dorsal medial prefrontal cortex and the temporal-parietal juncture—that govern similar understanding in adults.

"For a while now, we have known that specific brain areas are used when adults think about others' thoughts," according to Mark A. Sabbagh, associate professor of psychology at Queen's University at Kingston and the study's lead author. "Our findings are the first to show that these specialized neural circuits may be there as early as the preschool years, and that maturational changes in these areas are associated with preschoolers' abilities to think about their social world in increasingly sophisticated ways.

I wonder whether brain scans of 5 year olds can show which ones will grow up by be highly skilled at handling other people and which will do poorly at relating to others.

By Randall Parker    2009 July 15 10:33 PM   Entry Permalink | Comments (2)
2009 April 15 Wednesday
Prenatal Methamphetamine Alters Fetal Brain Development

Pregnant women using meth are messing up their babies. How about locking them up until the babies are born?

ST. PAUL, Minn. – A first of its kind study examining the effects of methamphetamine use during pregnancy has found the drug appears to cause abnormal brain development in children. The research is published in the April 15, 2009, online issue of Neurology®, the medical journal of the American Academy of Neurology.

"Methamphetamine use is an increasing problem among women of childbearing age, leading to an increasing number of children with prenatal meth exposure," said study author Linda Chang, MD, with the John A. Burns School of Medicine, University of Hawaii at Manoa in Honolulu. "But until now, the effects of prenatal meth exposure on the developing brain of a child were little known."

For the study, brain scans were performed on 29 three and four-year-old children whose mothers used meth while pregnant and 37 unexposed children of the same ages. The MRI scans used diffusion tensor imaging to help measure the diffusion of molecules in a child's brain, which can indicate abnormal microscopic brain structures that might reflect abnormal brain development.

The scans showed that children with prenatal meth exposure had differences in the white matter structure and maturation of their brains compared to unexposed children. The children with prenatal meth exposure had up to four percent lower diffusion of molecules in the white matter of their brains.

The brain damage probably lasts for life. We shouldn't let women do this to their babies. We all pay for it for decades to come.

The antiepilepsy drug valproate also messes up prenatal brain development.

Three-year-olds whose mothers took the antiepileptic drug valproate during pregnancy had average IQs six to nine points lower than children exposed to three other antiepileptic drugs, a landmark multi-center study has found.

The study's authors say that women of childbearing age should avoid valproate as a first choice drug for the treatment of epilepsy. The results are published in the April 16, 2009, issue of the New England Journal of Medicine.

By Randall Parker    2009 April 15 09:55 PM   Entry Permalink | Comments (8)
2008 November 20 Thursday
Hyperactive Boys Have Smaller Basal Ganglia In Brain

Boys with Attention Deficit Hyperactivity Disorder (ADHD) have brain shapes that differ from those kids who aren't hyperactive.

November 17, 2008 (Baltimore, MD)—A study published today in the online advance edition of The American Journal of Psychiatry for the first time reveals shape differences in the brains of children with ADHD, which could help pinpoint the specific neural circuits involved in the disorder. Researchers from the Kennedy Krieger Institute in Baltimore, Md. and the Johns Hopkins Center for Imaging Science used a new analysis tool, large deformation diffeomorphic mapping (LDDMM), which allowed them to examine the precise shape of the basal ganglia. The study found boys with ADHD had significant shape differences and decreases in overall volume of the basal ganglia compared to their typically developing peers. Girls with ADHD did not have volume or shape differences, suggesting sex strongly influences the disorder's expression.

Once again another discovery is made possible by a new measurement technique. The ability to more accurately scan and measure brain volumes allows scientists to discern differences in brain shapes that are correlated with behavioral differences.

Previous studies examining the basal ganglia in children with ADHD were limited to volume analysis and had conflicting results, with some reporting a smaller volume and some reporting no difference in volume. LDDMM provides detailed analysis of the shape of specific brain regions, allowing for precise examination of brain structures well beyond what has been examined in previous MRI studies of ADHD. In this study, LDDMM was used to map the brains of typically developing children in order to generate a basal ganglia template. This is the first reported template of the basal ganglia. After creating LDDMM mappings of the basal ganglia of each child with ADHD, statistical analysis was conducted to compare them to the template.

In this study, the initial volume analysis revealed boys with ADHD had significantly smaller basal ganglia volumes compared with typically-developing boys. Moving beyond the standard volume analysis, the LDDMM revealed shape abnormalities in several regions of the basal ganglia. Comparison of the standard volume and LDDMM analysis of girls with ADHD and their typically developing peers failed to reveal any significant volume or shape differences.

The multiple shape differences found in boys with ADHD suggests that the disorder may not be associated with abnormalities in one specific neural circuit. Rather, it appears the disorder involves abnormalities in parallel circuits, including circuits important for the control of complex behavior and more basic motor responses, such as hitting the brake pedal when a traffic light turns yellow. Findings revealing abnormalities in circuits important for basic motor response control may be crucial to understanding why children with ADHD have difficulty suppressing impulsive actions.

If this finding holds up it suggests that permanent reduction in ADHD behavior might require large scale changes in brain shape.

By Randall Parker    2008 November 20 11:50 PM   Entry Permalink | Comments (0)
2008 September 25 Thursday
8 Year Olds Learn Little From Negative Feedback

By age of 12 children show adult patterns of brain response to negative feedback.

Eight-year-old children have a radically different learning strategy from twelve-year-olds and adults. Eight-year-olds learn primarily from positive feedback ('Well done!'), whereas negative feedback ('Got it wrong this time') scarcely causes any alarm bells to ring. Twelve-year-olds are better able to process negative feedback, and use it to learn from their mistakes. Adults do the same, but more efficiently.

The switch in learning strategy has been demonstrated in behavioural research, which shows that eight-year-olds respond disproportionately inaccurately to negative feedback. But the switch can also be seen in the brain, as developmental psychologist Dr Eveline Crone and her colleagues from the Leiden Brain and Cognition Lab discovered using fMRI research. The difference can be observed particularly in the areas of the brain responsible for cognitive control. These areas are located in the cerebral cortex.

In children of eight and nine, these areas of the brain react strongly to positive feedback and scarcely respond at all to negative feedback. But in children of 12 and 13, and also in adults, the opposite is the case. Their 'control centres' in the brain are more strongly activated by negative feedback and much less by positive feedback.

What I wonder: Do some people fail to make the transition toward reacting more to negative feedback? Are some adults neurologically not wired up to learn from negative feedback? Likely the extent of the shift differs from person to person as they grow up and the timing of the shift differs as well.

By Randall Parker    2008 September 25 11:20 PM   Entry Permalink | Comments (1)
2008 September 09 Tuesday
Fish Consumption And Breast Feeding Boost Infant Brain Development

Eating fish during pregnancy and longer periods of breast feeding boost brain development.

BOSTON, Mass. (Sept. 9, 2008) — Both higher fish consumption and longer breastfeeding are linked to better physical and cognitive development in infants, according to a study of mothers and infants from Denmark. Maternal fish consumption and longer breastfeeding were independently beneficial.

"These results, together with findings from other studies of women in the U.S. and the United Kingdom, provide additional evidence that moderate maternal fish intake during pregnancy does not harm child development and may on balance be beneficial," said Assistant Professor Emily Oken, lead author of the study.

The study, which appeared in the September issue of the American Journal of Clinical Nutrition, was conducted by researchers from the Department of Ambulatory Care and Prevention of Harvard Medical School and Harvard Pilgrim Health Care and the Maternal Nutrition Group from the Department of Epidemiology at Statens Serum Institut in Copenhagen, Denmark. These findings provide further evidence that the omega-3 fatty acids found in fish and compounds in breast milk are beneficial to infant development.

The study team looked at 25,446 children born to mothers participating in the Danish Birth Cohort, a study that includes pregnant women enrolled from 1997-2002. Mothers were interviewed about child development markers at 6 and 18 months postpartum and asked about their breastfeeding at 6 months postpartum. Prenatal diet, including amounts and types of fish consumed weekly, was assessed by a detailed food frequency questionnaire administered when they were six months pregnant.

During the interviews mothers were asked about specific physical and cognitive developmental milestones such as whether the child at six months could hold up his/her head, sit with a straight back, sit unsupported, respond to sound or voices, imitate sounds, or crawl. At 18 months, they were asked about more advanced milestones such as whether the child could climb stairs, remove his/her socks, drink from a cup, write or draw, use word-like sounds and put words together, and whether they could walk unassisted.

The children whose mothers ate the most fish during pregnancy were more likely to have better motor and cognitive skills. For example, among mothers who ate the least fish, 5.7% of their children had the lowest developmental scores at 18 months, compared with only 3.7% of children whose mothers had the highest fish intake. Compared with women who ate the least fish, women with the highest fish intake (about 60 grams - 2 ounces - per day on average) had children 25% more likely to have higher developmental scores at 6 months and almost 30% more likely to have higher scores at 18 months.

Longer duration of breastfeeding was also associated with better infant development, especially at 18 months. Breastmilk also contains omega-3 fatty acids. The benefit of fish consumption was similar among infants breastfed for shorter or longer durations.

Ladies, select fish that are low in mercury. Or take fish oil pills.

So then if fish consumption causes greater development of the anterior prefrontal cortex will the kids raised with more omega 3 fatty acids exercise more self control? Do fish boost free will?

Other ways to optimize brain development exist. Higher calcium consumption during pregnancy might reduce fetal lead exposure.

ANN ARBOR, Mich.---Pregnant women who take high levels of daily calcium supplements show a marked reduction in lead levels in their blood, suggesting calcium could play a critical role in reducing fetal and infant exposure.

A new study at the University of Michigan shows that women who take 1,200 milligrams of calcium daily have up to a 31 percent reduction in lead levels.

Women who used lead-glazed ceramics and those with high bone lead levels showed the largest reductions; the average reduction was about 11 percent, said Howard Hu, chair of the Department of Environmental Health Sciences at the School of Public Health.

By Randall Parker    2008 September 09 11:14 PM   Entry Permalink | Comments (3)
2008 August 18 Monday
Babies React More To Fearful Faces At 6 Months

Somewhere around 6 months of age babies suddenly start paying much more attention to fearful faces.

Scientists working in the Academy-funded Research Programme on Neuroscience (NEURO) have discovered important changes in the way that infants react to another person’s face at age 5–7 months.

Infants aged 5 months react very differently to a fearful face than those aged 7 months. “At the age of 7 months babies will watch a fearful face for longer than a happy face, and their attentiveness level as measured by EEG is higher after seeing a fearful than a happy face. By contrast, infants aged 5 months watch both faces, when they are shown side by side, for just as long, and there is no difference in the intensity of attention in favour of the fearful face,” said Mikko Peltola, researcher at the University of Tampere, at the Academy’s Science Breakfast this week.

It seems that at age 6 months, important developmental changes take place in the way that infants process significant emotional expressions. A fearful face attracts intense attention by the age of 7 months. In addition, it takes longer for infants to shift their attention away from fearful than from happy and neutral faces.

I wonder how much variability there is in when this transition happens. Also, do babies with Asperger's Syndrome or autism go through this same transition in how they react to fearful faces and do they do this at the same point in time as normal children?

Also, is the intense attention to fearful faces a defense mechanism? Or is it a pointless reaction at age 6 months but a capability that needs to come sooner or later which just happens to occur at 6 months?

By Randall Parker    2008 August 18 09:56 PM   Entry Permalink | Comments (0)
2008 May 28 Wednesday
Lead Exposure Boosts Incidence Of Criminality?

The neurotoxin lead appears to have long term negative effects on behavior.

Childhood exposure to lead is associated with adult criminal behaviour, including violent crime, finds a new study in this week’s PLoS Medicine. Dr Kim Dietrich and colleagues (University of Cincinnati, USA) studied the association between exposure to lead in the uterus and during early childhood and criminal arrests in adulthood, in poor areas of Cincinnati.

Lead is known to be toxic to the nervous system. Childhood exposure has been identified as a potential risk factor for antisocial behaviour in adulthood. But this link has relied on indirect measurement of childhood lead exposure in adults or has measured childhood lead exposure directly but has not followed lead-exposed children into adulthood. The new study overcomes both of these limitations.

Between 1979 and 1984, the researchers recruited pregnant women living in poor areas of Cincinnati, which had a high concentration of older lead-contaminated housing. Out of the 376 newborns recruited into the study, 250 were included in the final analysis. Blood lead levels were measured during pregnancy and then regularly until the children were six and a half years old, as an indication of their lead exposure. This exposure was then correlated with local criminal justice records on how many times each of the 250 offspring had been arrested between becoming 18 years old and the end of October 2005.

The researchers found that increased blood lead levels before birth and during early childhood were associated with higher rates of arrest for any reason and for violent crimes. For example, for every 5ug/dl increase in blood lead levels at six years of age, the risk of being arrested for a violent crime as a young adult increased by almost 50% (the “relative risk” was 1.48).

Here is the full research paper.

Testing 5 year olds or maybe 3 year olds for blood lead levels followed by measures to lower lead levels could pay rich dividends in lower crime rates. Note that a lot of evidence points toward the idea that vitamin B1 (thiamin) seems to increase excretion of lead. A few other nutrients might do so as well.

By Randall Parker    2008 May 28 07:11 PM   Entry Permalink | Comments (13)
2008 April 23 Wednesday
Teen Brains Get Restructured During Development

Teens can be so messed up because their brains are getting restructured.

Philadelphia, March 28, 2008 – Many parents are convinced that the brains of their teenage offspring are different than those of children and adults. New data confirms that this is the case. An article by Jay N. Giedd, MD, of the National Institute of Mental Health (NIMH), published in the April 2008 issue of the Journal of Adolescent Health describes how brain changes in the adolescent brain impact cognition, emotion and behavior.

Dr. Giedd reviews the results from the NIMH Longitudinal Brain Imaging Project. This study and others indicate that gray matter increases in volume until approximately the early teens and then decreases until old age. Pinning down these differences in a rigorous way had been elusive until MRI was developed, offering the capacity to provide extremely accurate quantifications of brain anatomy and physiology without the use of ionizing radiation.

Our brains go through big changes during adolescence. The brain gets a lot of executive function enhancements.

The NIMH Longitudinal Brain Imaging Project began in 1989. Participants visit the NIMH at approximately two-year intervals for brain imaging, neuropsychological and behavioral assessment and collection of DNA. As of September 2007, approximately 5000 scans from 2000 subjects have been acquired. Of these, 387 subjects, aged 3 to 27 years, have remained free of any psychopathology and serve as the models for typical brain development.

Three themes have emerged from this and other studies in this new era of adolescent neuroscience. The first is functional and structural increases in connectivity and integrative processing as distributed brain modules become more and more integrated. Using a literary metaphor, maturation would not be the addition of new letters but rather of combining earlier formed letters into words, and then words into sentences and then sentences into paragraphs.

The second is a general pattern of childhood peaks of gray matter (frontal lobe, parietal lobe, temporal lobe and occipital lobe) followed by adolescent declines. As parts of the brain are overdeveloped and then discarded, the structure of the brain becomes more refined.

The third theme is a changing balance between limbic/subcortical and frontal lobe functions that extends well into young adulthood as different cognitive and emotional systems mature at different rates. The cognitive and behavioral changes taking place during adolescence may be understood from the perspective of increased “executive” functioning, a term encompassing a broad array of abilities, including attention, response inhibition, regulation of emotion, organization and long-range planning.

What would be helpful: ways to identify when a kid's brain development has entered a stage which makes them more dangerous to self or other due. Detect a deficiency of functions that make them better able to understand themselves and others and more able to restraint their actions.

I can imagine some day drivers license requirements will include brain scans to show that one is not obviously prone to rash and dangerous actions. Also, I can imagine the development of drugs that will speed a teenager more quickly through stages since moms would just as soon have kids with more mature personalities once the kids hit adolescence.

By Randall Parker    2008 April 23 10:50 PM   Entry Permalink | Comments (6)
2008 April 10 Thursday
Omega 3 Fatty Acids Boost Fetal Brain Development?

The omega 3 fatty acid is suspected of boosting infant brain development.

Quebec City, April 9, 2008—A study supervised by Université Laval researchers Gina Muckle and Éric Dewailly reveals that omega-3 intake during the last months of pregnancy boosts an infant’s sensory, cognitive, and motor development. The details of this finding are published in a recent edition of the Journal of Pediatrics.

To come to this conclusion, researchers first measured docosahexaenoic acid (DHA) concentration—a type of omega-3 fatty acid involved in the development of neurons and retinas—in the umbilical cord blood of 109 infants. “DHA concentration in the umbilical cord is a good indicator of intra-uterine exposure to omega-3s during the last trimester of pregnancy, a crucial period for the development of retinal photoreceptors and neurons,” explains Dr. Dewailly.

Tests conducted on these infants at 6 and 11 months revealed that their visual acuity as well as their cognitive and motor development were closely linked to DHA concentration in the umbilical cord blood at the time of their birth. However, there was very little relation between test results and DHA concentration in a mother’s milk among infants who were breast-fed. “These results highlight the crucial importance of prenatal exposure to omega-3s in a child’s development,” points out Dr. Muckle.

This is not the first study to make that claim. But a lot of factors influence intellectual development including genetics. It is hard to prove the influence of this one factor. Still, given DHA's role in nerve cell membranes this claim seems highly plausible.

By Randall Parker    2008 April 10 11:01 PM   Entry Permalink | Comments (2)
2008 March 23 Sunday
Childhood Personality Partially Predicts Later Life Stages

These results deal with averages of course. But personality types identifiable in preschool children have lasting effects.

Participants consisted of 230 children who were studied every year from their first or second year in preschool until age 12. After age 12, the sample was reassessed twice, at ages 17 and 23. Researchers led by Jaap Denissen of Humboldt-University Berlin assessed degrees of shyness and aggressiveness through parental scales and teacher reports.

Denissen tested the hypotheses on the predictive validity of three major preschool personality types. Resilient personality is characterized by above average emotional stability, IQ, and academic achievement. Overcontrol is characterized by low scores on extraversion, emotional stability, and self-esteem. Undercontrol is characterized by low scores on emotional stability and agreeableness and high scores on aggressive behavior.

The 19-year longitudinal study illustrated that childhood personality types were meaningfully associated with the timing of the transitions. Resilient males were found to leave their parents’ house approximately one year earlier than overcontrolled or undercontrolled children. Overcontrolled boys took more than a year longer than others in finding a romantic partner. Resilient boys and girls were faster in getting a part-time job than their overcontrolled and undercontrolled peers.

Okay, when offspring genetic engineering becomes possible will prospective parents opt to give their kids genetic variations that make them resilient personalities or maybe undercontrolled or overcontrolled? I'm expecting parents to boost the IQ of their kids. But will they go too far in giving the kids extraversion or perhaps make them too emotionally controlled?

By Randall Parker    2008 March 23 10:23 PM   Entry Permalink | Comments (1)
2008 March 09 Sunday
Brain Gene Makes Abused Kids More Prone To Depression

Some kids have genes that make them better able to handle abuse with fewer long term repercussions.

Some forms of a gene that controls the body's response to stress hormones appear to protect adults who were abused in childhood from depression, psychiatrists have found.

People who had been abused as children and who carried the most protective forms of the gene, called corticotropin-releasing hormone receptor one (CRHR1), had markedly lower measures of depression, compared with people with less protective forms, the researchers found in a recent study.

The findings could guide doctors in finding new ways to treat depression in people who were abused as children, says senior author Kerry Ressler, MD, PhD, assistant professor of psychiatry and behavioral sciences at Emory University School of Medicine.

This is not the first report of genetic variations of brain genes that affect how well developing children handle abuse and adversity. Previous research found that children who carry the low MAOA activity allele (MAOA-L) and who are abused demonstrate more aggressive and violent behavior as adults.

Some kids have genes that let them shrug off all sorts of abuse and basically keep trucking. Other kids aren't so lucky. Those latter kids become problems for the rest of us too. Violence prone adults pose a danger to whoever they come into contact with.

Early identification of kids with genetic vulnerabilities might some day get used to guide more aggressive state intervention into bad families. You can imagine social workers arguing to take a kid out of an abusive home more quickly if the has genes that make him or her vulnerable to permanent and problematic behavioral and personality alterations.

Once offspring genetic engineering becomes possible we can't assume parents should avoid giving offspring these genetic variations that make kids more vulnerable to abuse. There might be benefits to these alleles in more benign environments. Though I see a more compelling argument for discouraging the passing along of these alleles if either prospective parent has a genetic profile and brain scans that suggests he or she is likely to abuse kids.

By Randall Parker    2008 March 09 10:30 PM   Entry Permalink | Comments (0)
2008 February 25 Monday
Bratty Adolescents Have Bigger Amygdalas

A team of scientists at the University of Melbourne in Australia watched some 11 to 14 year old early adolescent children discuss points of disagreement with their parents and measured their reactions. Then the scientists measured the size of brain areas in each of the children. Well, the children more prone to tantrums and sulking had different sizes of various brain areas as compared to the more agreeable children. Is anyone surprised by this result?

Next the team scanned the children’s brains, focusing on three regions: the amygdala, which triggers impulsive reactions to emotional situations, and the anterior cingulate cortex (ACC) and orbitofrontal cortex (OFC) – pre-frontal parts of the brain involved in more thoughtful and reflective responses.

Children of both sexes who behaved more aggressively during the problem-solving tasks had bigger amygdalas, while boys who had smaller ACCs on the left side of the brain, compared with the right, stayed aggressive for longer. Also, boys with smaller OFCs on the left side were more likely to respond to a parent’s sulky behaviour with a sulk of their own.

Picture our genetically engineered future. I expect many prospective parents to opt to give their offspring genetic variations that will make their brains develop bigger anterior cingulate cortex (ACC) and orbitofrontal cortex (OFC) brain regions and to develop those regions sooner during adolescence. Just genetically engineer surliness and brattiness right out of kids. Why not?

From the abstract of the PNAS paper:

In a sample of 137 early adolescents, we investigated the relationship between aspects of the adolescents' brain structure and their affective behavior as assessed during observation of parent–child interactions. We found a significant positive association between volume of the amygdala and the duration of adolescent aggressive behavior during these interactions. We also found male-specific associations between the volume of prefrontal structures and affective behavior, with decreased leftward anterior paralimbic cortex volume asymmetry associated with increased duration of aggressive behavior, and decreased leftward orbitofrontal cortex volume asymmetry associated with increased reciprocity of dysphoric behavior. These findings suggest that adolescent brain structure is associated with affective behavior and its regulation in the context of family interactions, and that there may be gender differences in the neural mechanisms underlying affective and behavioral regulation during early adolescence. Particularly as adolescence marks a period of rapid brain maturation, our findings have implications for mental health outcomes that may be revealed later along the developmental trajectory.

For most kids the bratty punk surly rude inconsiderate phase won't last. But the behavior of some adults suggests that not all escape from this phase. These who get stuck in adolescence probably need brain gene therapy to push their brains along a sorely needed development path.

Team leader Nicholas Allen, a clinical psychologist with the University of Melbourne and the Orygen Research Centre, said: "The good news is that to a certain extent it's a phase. Parents do find it helpful to understand that some of the inexplicable behaviours teenagers come up with is part of a brain developmental phase."

What were you thinking?

Professor Allen said that the research also cast light on why teenagers who one day approached tasks with a maturity beyond their years could act with immaturity the next. “Your 6ft 2 son can manage some very complicated work yet still do these dumb things. ‘What were you thinking?’ has been asked by every parent of teenagers,” he said.

Also see my previous post Adolescence Is Tough On The Brain.

By Randall Parker    2008 February 25 10:36 PM   Entry Permalink | Comments (1)
2007 November 23 Friday
Even Low Blood Lead Levels Lower IQ?

Lead toxicity to the brain appears to kick in at pretty low blood levels of lead.

Even very small amounts of lead in children's blood -- amounts well below the current federal standard -- are associated with reduced IQ scores, finds a new six-year Cornell study.

The study examined the effect of lead exposure on cognitive function in children whose blood-lead levels (BLLs) were below the Centers for Disease Control and Prevention (CDC) standard of 10 micrograms per deciliter (mcg/dl) -- about 100 parts per billion. The researchers compared children whose BLLs were between 0 and 5 mcg/dl with children in the 5-10 mcg/dl range.

"Even after taking into consideration family and environmental factors known to affect a child's cognitive performance, blood lead played a significant role in predicting nonverbal IQ scores," says Richard Canfield, a senior researcher in Cornell's Division of Nutritional Sciences and senior author of the study in the journal Environmental Health Perspectives. "We found that the average IQ scores of children with BLLs of only 5 to 10 mcg/dl were about 5 points lower than the IQ scores of children with BLLs less than 5 mcg/dl. This indicates an adverse effect on children who have a BLL substantially below the CDC standard, suggesting the need for more stringent regulations," he said.

Vitamin C (ascorbic acid) and B1 (thiamine) enhance lead excretion. Screening of children in high risk neighborhoods might identify neighborhoods where children should take a multivitamin that will raise their IQs by reducing lead toxicity. A 5 point IQ jump would pay back the cost of the screening and vitamins many times over.

By Randall Parker    2007 November 23 11:26 PM   Entry Permalink | Comments (11)
2007 November 15 Thursday
ADHD Kids Have Slower Developing Brains

Kids with attention deficit experience brain growth in some areas their brains 3 years later than non-ADHD kids.

In youth with attention deficit hyperactivity disorder (ADHD), the brain matures in a normal pattern but is delayed three years in some regions, on average, compared to youth without the disorder, an imaging study by researchers at the National Institutes of Health’s (NIH) National Institute of Mental Health (NIMH) has revealed. The delay in ADHD was most prominent in regions at the front of the brain’s outer mantle (cortex), important for the ability to control thinking, attention and planning. Otherwise, both groups showed a similar back-to-front wave of brain maturation with different areas peaking in thickness at different times (see movie below).

“Finding a normal pattern of cortex maturation, albeit delayed, in children with ADHD should be reassuring to families and could help to explain why many youth eventually seem to grow out of the disorder,” explained Philip Shaw, M.D., NIMH Child Psychiatry Branch, who led research team.

So then maybe all those ADHD boys shouldn't be on Ritalin. Maybe we should let restless boys be restless and not expect them to act like calm girls.

Do ADHD kids who took Ritalin for years demonstrate higher or lower cognitive performance as adults than ADHD kids who do not take Ritalin?

Also, while I'm asking: Do the brains of ADHD kids develop more slowly because of genes, nutrition, or some other reason? I'm guessing it is at least partly genetic.

By Randall Parker    2007 November 15 11:33 PM   Entry Permalink | Comments (2)
2007 November 10 Saturday
Curvy Women Have Smarter Kids

Children whose mothers have lower waist-hip ratio (WHR) are smarter.

Upper-body fat has negative effects and lower-body fat has positive effects on the supply of long-chain polyunsaturated fatty acids that are essential for neurodevelopment. Thus, waist-hip ratio (WHR), a useful proxy for the ratio of upper-body fat to lower-body fat, should predict cognitive ability in women and their offspring. Moreover, because teenage mothers and their children compete for these resources, their cognitive development should be compromised, but less so for mothers with lower WHRs. These predictions are supported by data from the Third National Health and Nutrition Examination Survey. Controlling for other correlates of cognitive ability, women with lower WHRs and their children have significantly higher cognitive test scores, and teenage mothers with lower WHRs and their children are protected from cognitive decrements associated with teen births. These findings support the idea that WHR reflects the availability of neurodevelopmental resources and thus offer a new explanation for men's preference for low WHR.

They suspect the omega-3 fatty acids in particular as beneficial. So women should eat salmon while pregnant and while nursing.

The answer could be encountered in omega-3 fatty acids, stored in the hips and thighs and which make a large percentage of the human brain. This type of fatty acids is stored by the female body below the waist with the installation of the puberty.

The male obsession with curviness shows how responsible we are to want smarter kids.

"Men respond because it's reproductively important," Lassek says.

This is not the only evolutionary reason why men prefer curvier women. Women With Hourglass Bodies Have More Reproductive Hormones.

What I wonder: Does the draining of omega 3 fatty acids from a woman in the last trimester of pregnancy contribute to post-partum depression? Check out some of the evidence on omega 3 fatty acids and depression here and here and here.

Also see my post Higher Fish Diet Seems To Make Babies Smarter.

Update: In fact, Joseph R. Hibbeln of the National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, has found evidence that postpartum depression is more common among women with lower omega 3 fatty acids (PDF format).

Higher fish consumption looks highly beneficial as protection against postpartum depression.

The new study is an analysis of 11,721 British women. Researchers found that the more omega-3 fatty acids a woman consumed in seafood during the third trimester, the less likely she was to show signs of major depression at that time and for up to eight months after the birth.

In fact, the rate of depression in the women with the highest intakes was only about half that of women with the lowest intakes, says senior author and psychiatrist Dr. Joseph R. Hibbeln.

Omega 3 fatty acids is one of the two nutrients most people should try to get more of. Vitamin D is the other one. Go for salmon and sardines to get more omega 3 fatty acids. It'll even reduce the chances you'll commit a crime.

By Randall Parker    2007 November 10 09:40 AM   Entry Permalink | Comments (5)
2007 November 06 Tuesday
Gene Boosts IQ Benefit Of Breast Feeding

Here is news some new moms can use. Whether breast feeding will boost offspring IQ comes down to which genetic variations the babies carry.

DURHAM, N.C. – The known association between breast feeding and slightly higher IQ in children has been shown to relate to a particular gene in the babies, according to a report this week in the Proceedings of the National Academy of Sciences.

In two studies of breast-fed infants involving more than 3,000 children in Britain and New Zealand, breastfeeding was found to raise intelligence an average of nearly 7 IQ points if the children had a particular version of a gene called FADS2.

The distribution of FADS2 genetic variants probably varies around the world. Anyone know of a source of data for FADS2 genetic variant distributions in human races and local ethnic groups? That information would probably indicate whether results would hold up in all human populations.

"There has been some criticism of earlier studies about breastfeeding and IQ that they didn't control for socioeconomic status, or the mother's IQ or other factors, but our findings take an end-run around those arguments by showing the physiological mechanism that accounts for the difference," said Terrie Moffitt, a professor of psychological and brain sciences in Duke University's Institute for Genome Sciences and Policy.

Moffitt, who performed the research with her husband and co-author Avshalom Caspi at King's College in London, found that the baby's intellectual development is influenced by both genes and environment or, more specifically, by the interaction of its genes with its environment.

"The argument about intelligence has been about nature versus nurture for at least a century," Moffitt said. "We're finding that nature and nurture work together."

These results suggest that most women should breast feed. Only 10% of the women in the study groups had babies with genetic profiles which prevented a benefit from breast feeding.

Ninety percent of the children in the two study groups had at least one copy of the "C" version of FADS2, which yielded higher IQ if they were breast-fed. The other 10 percent, with only the "G" versions of the gene, showed no IQ advantage or disadvantage from breastfeeding.

A cheap test for FADS2 variants could help millions of women weigh the costs and benefits of breast feeding. Find out from a genetic test whether newly born junior will turn out smarter if you structure your life so that breast feeding is practical.

The benefit of the "C" version of FADS2 might come from its ability to convert other fatty acids to DHA.

The gene was singled out for the researchers' attention because it produces an enzyme that helps convert dietary fatty acids into the polyunsaturated fatty acids DHA (docosahexaenoic acid) and AA (arachidonic acid) that have been shown to accumulate in the human brain during the first months after birth.

A baby formula high in DHA might deliver the same benefit as breast feeding and deliver that benefit regardless of genetic variations carried by a baby. Mom eating salmon every day and then breast feeding might similarly deliver that benefit regardless of genetic variation.

A 7 point IQ boost is a really big deal. A country that boosted its average IQ by 7 points would experience a huge boost in economic growth and a rise in per capita GDP as the smarter kids made their way into the labor market.

By Randall Parker    2007 November 06 08:25 PM   Entry Permalink | Comments (5)
2007 October 09 Tuesday
Video Viewing Not Seen As Benefit For Baby Learning

Special videos not magic mental development tool for babies.

The Seattle team surveyed more than 1,000 families in February 2006 and found that infants between 8 and 16 months who regularly watched Baby Einstein and Brainy Baby videos knew substantially fewer words -- six to eight out of 90 -- than infants who did not watch them, according to parental reports. The deficit, which increased with each hour of video viewing, was not seen among babies who watched other programming, such as "Sesame Street" or "SpongeBob SquarePants" or adult shows such as "Oprah."

The study, published in the Journal of Pediatrics, is the first to examine the impact of videos that have been heavily promoted as educational, according to lead author Frederick J. Zimmerman, a University of Washington associate professor of public health and pediatrics. Zimmerman called the negative effect "large and significant" but said the study stopped short of establishing a causal connection.

I would expect babies to learn more from interacting with humans since interactions provide feedbacks on what they do.

What is striking to me about a story like this one is the lengths that some people will go to try to boost the mental development of little Johnnie and Jill. Imagine what parents will do once real mental boosting biotechnologies become available. A drug that boosts IQ by 10 points if taken for several years during childhood would be a big seller. But at least in some of the Western industrialized countries getting such drugs approved will be very difficult. The problem of how to prove safety is enormous. This leads me to expect bigger IQ boosts will happen in less developed countries which lack big drug regulatory agencies.

Much bigger IQ boosts will become available via genetic tinkering at the time of conception. The use of multiple embryos with pre-implantation genetic diagnosis (aka PIGD or PGD) to choose the potentially smartest embryo will a face fewer regulatory obstacles than the use of gene therapy to modify embryo genes. But the latter will offer far greater potential for intellectual boosting once scientists identify all the genetic variations that influence intelligence and once embryo genetic engineering techniques become fairly mature and safe.

By Randall Parker    2007 October 09 05:21 PM   Entry Permalink | Comments (3)
2007 October 06 Saturday
More Fish For Pregnant Women?

More fish for developing fetuses?

Washington, D.C. ---- Today a Maternal Nutrition Group comprised of top professors of obstetrics and doctors of nutrition from across the country, in partnership with the National Healthy Mothers, Healthy Babies Coalition (HMHB), unveiled recommendations for seafood consumption during pregnancy. The recommendations come at a time when the debate about mercury in fish and an FDA/EPA advisory have created confusion for pregnant women, causing a reduction in their fish consumption. This leads to inadequate intake of omega-3 fatty acids resulting in risks to their health and the health of their children. This inadequate intake of fish is confirmed by data from the National Health and Nutrition Examination Survey (NHANES), which shows that 90 percent of women are consuming less than the FDA-recommended amount of fish.

The Group recommended that women who want to become pregnant, are pregnant or are breastfeeding should eat a minimum of 12 ounces per week of fish like salmon, tuna, sardines and mackerel, and can do so safely. The Group found that eating fish is the optimal way to gain the benefits of long-chain omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Seafood is the richest dietary source of DHA and EPA in Americans’ diets. The Group also recognized that selenium, an essential mineral found in certain ocean fish, accumulates and appears to protect against the toxicity from trace amounts of mercury.

This advice is controversial and disputed by some. Also see here. Currently the US Food and Drug Administration recommends a maximum of 12 ounces of low mercury fish for pregnant women. But given the enormous range of mercury concentrations found in different fish species I think their advice should have been more nuanced. What is the justification for restricting salmon consumption to 12 ounces per week for example? Salmon is one of the richest omega 3 sources (and yours truly eats it 5 times a week on average) and salmon has very little mercury in it.

Omega 3 fatty acids are likely to boost baby intelligence, reduce the incidence of auto-immune diseases, delay Alzheimer's disease, reduce risk of macular degeneration, and reduce all-cause mortality. Omega 3s also appear to reduce depression and increase brain grey matter. Also, in practice the omega 3 fatty acids in fish seem to benefit babies more than the mercury might hurt them. My take: Omega 3 fatty acids deliver so many health benefits and fish sources are in such limited supply that we need seed companies to genetically engineer into grains the enzymes for making omega 3 fatty acids. Or how about transgenic pigs that make omega 3 fatty acids?

By Randall Parker    2007 October 06 04:52 PM   Entry Permalink | Comments (9)
2007 August 18 Saturday
Two Brain Control Networks Merged In Children

Two brain control networks found in adults exist as a single merged control network in children.

Two recently discovered control networks that govern voluntary brain activity in adults start life as a single network in children, report neuroscientists at Washington University School of Medicine in St. Louis.

Researchers previously showed the networks supervise most goal-oriented brain activity, enlisting the specialized talents of multiple brain regions for goal-oriented tasks as diverse as reading a word, listening to music or searching for a star. They were surprised to find the two networks merged together in children.

Kids don't just know a lot less. They think differently. Okay, you already knew that. But it is still great when science confirms our observations about human nature. Also, this sort of research is a useful lesson for those who try to force kids to act like adults.

A new brain scanning method made this discovery possible.

Scientists used a new brain scanning technique called resting state functional connectivity MRI to identify the control networks. Instead of analyzing mental activity when a volunteer works on a cognitive task, the new technique scans their brains while they do nothing. The scans reveal changes in the levels of oxygen in blood flowing to different areas of the brain. Researchers interpret correlations in the rise and fall of blood oxygen to different brain areas during inactivity as a sign that those areas likely work together. In neuroscientist's terms, this means the regions have functional connectivity.

A team of researchers led by Petersen and M.D./Ph.D. student Nico Dosenbach analyzed scans of volunteers with an approach called graph theory. They represented various brain regions of interest as shapes, and when two regions met a threshold for functional connectivity, they drew a line between them. The two control networks were distinctly separate even when the connectivity threshold was set to a low level.

For the new study, scientists used the same techniques to analyze the brains of 210 children, adolescents and adults. They found the two control networks are merged in children but begin pulling apart in adolescents, establishing themselves as separate entities and becoming more complex.

Some people complain that adolescents are so weird. To those people I ask: How would you act if your brain was undergoing a major reorganization of how it controls itself?

The brain continues to change as we get older.

Fair notes that an interesting pattern emerged as scientists looked at their data from a big picture perspective.

"As we get older, connections that are getting weaker tend to be between brain regions located close to each other, while the connections that are getting stronger tend be those between regions that are far apart," he says.

I'm skeptical of claims that there's a single best standard for aesthetic issues. Given that humans differ so much in how their brains are wired up we should expect people to differ in their tastes in music, architecture, annoyance at noise, desire to drive fast, and in countless other ways. This isn't to argue that every state of mind is equally morally justifiable. Murderers aren't justified in murdering just because some might be wired up to strongly want to murder.

Brain research will eventually present challenges when some differences in values are found to derive from innate differences in brain architectures. Hard to argue that a disagreement is due to misunderstandings when the disagreement is the result of innate differences in how brains reason and form emotions.

Brain development research will probably change how we grant rights. Children have fewer rights (e.g. a very limited right to contract) in most societies. That's a recognition of the lower capacity of children to judge and to fulfill responsibilities. Well, once research can show that some fast developing 16 year olds have a greater capacity to evaluate and fulfill obligations in contracts than some 25 year olds why should all 25 year olds have more rights than all 16 year olds?

Instead of an all-or-little granting of rights might it make more sense to grant levels of rights and even categories of rights incrementally based on extent of cognitive capabilities? We lack the capability to measure small gradations in ability to respect rights or honor contracts. But that won't always be the case. I expect results of brain scans and other measurements of cognitive capability to some day get used by governments to determine when a person can get a driver's license, enlist in the military, or become an emancipated minor.

By Randall Parker    2007 August 18 11:00 AM   Entry Permalink | Comments (0)
2007 July 27 Friday
Better Connected Brains More Resistant To Peer Pressure?

Is susceptibility to peer pressure identifiable in adolescents using brain scans? ("but mom, my weak brain connections made it impossible for me to say no")

WASHINGTON, DC July 26, 2007 – Brain regions that regulate different aspects of behavior are more interconnected in children with high resistance to peer influence than those with low resistance, according to a new study published in the July 25 issue of The Journal of Neuroscience.

"These findings may help develop more effective strategies to prevent the development of lifestyles of violence and crime,” says John Sweeney, PhD, Director of the Center for Cognitive Medicine at the University of Illinois at Chicago. Sweeney was not involved in this study.

In the new study, Tomas Paus, MD, PhD, at the University of Nottingham, and his colleagues used functional neuroimaging to scan adolescents while they watched video clips of neutral or angry hand and face movements. Previous research has shown that anger is the most easily recognized emotion.

Paus and his team observed 35 10-year-olds with high and low resistance to peer influence, as determined by a questionnaire. The researchers then showed the children video clips of angry hand movements and angry faces and measured their brain activity. They found that the brains of all children showed activity in regions important for planning and extracting information about social cues from movement, but the connectivity between these regions was stronger in children who were marked as less vulnerable to peer influence. These children were also found to have more activity in the prefrontal cortex, an area important for decision making and inhibition of socially inappropriate behavior.

Do stronger connections between these brain regions form as these children with weaker connections get older? Or perhaps do they remain more susceptible to peer pressure?

By Randall Parker    2007 July 27 12:03 AM   Entry Permalink | Comments (2)
2007 May 09 Wednesday
Pesticides Make Dumber Summer-Conceived Babies?

Do babies conceived during summer perform worse at cognitive tasks?

INDIANAPOLIS — Does the time of year in which a child is conceived influence future academic achievement? Yes, according to research by neonatologist Paul Winchester, M.D., Indiana University School of Medicine professor of clinical pediatrics. Dr. Winchester, who studied 1,667,391 Indiana students, presents his finding on May 7 at the Pediatric Academic Societies' annual meeting.

Dr. Winchester and colleagues linked the scores of the students in grades 3 through 10 who took the Indiana Statewide Testing for Educational Progress (ISTEP) examination with the month in which each student had been conceived. The researchers found that ISTEP scores for math and language were distinctly seasonal with the lowest scores received by children who had been conceived in June through August.

Why might children conceived in June through August have the lowest ISTEP scores? "The fetal brain begins developing soon after conception. The pesticides we use to control pests in fields and our homes and the nitrates we use to fertilize crops and even our lawns are at their highest level in the summer," said Dr. Winchester, who also directs Newborn Intensive Care Services at St. Francis Hospital in Indianapolis.

"Exposure to pesticides and nitrates can alter the hormonal milieu of the pregnant mother and the developing fetal brain," said Dr. Winchester. "While our findings do not represent absolute proof that pesticides and nitrates contribute to lower ISTEP scores, they strongly support such a hypothesis."

I can think of many other potential explanations. For example, maybe the babies conceived in the summer do not get enough vitamin D in the winter and this lack of vitamin D causes their brains to develop poorly when their brains are developing most rapidly. Maybe nutritional status matters more during later months of pregnancy.

Pesticides might also be upping the rate of premature births.

INDIANAPOLIS — The growing premature birth rate in the United States appears to be strongly associated with increased use of pesticides and nitrates, according to work conducted by Paul Winchester, M.D., professor of clinical pediatrics at the Indiana University School of Medicine. He reports his findings May 7 at the Pediatric Academic Societies' annual meeting, a combined gathering of the American Pediatric Society, the Society for Pediatric Research, the Ambulatory Pediatric Association and the American Academy of Pediatrics.

Dr. Winchester and colleagues found that preterm birth rates peaked when pesticides and nitrates measurements in surface water were highest (April-July) and were lowest when nitrates and pesticides were lowest (Aug.-Sept.).

A repeat of this experiment in other regions could control for the pesticide effect since not all areas of the United States have much agriculture. Also, growing season start dates and lengths differ by region. The effect of pesticides would start later and end earlier in Maine than in Missouri for example. We could also see a difference depending on the source of water supply. Water supplies probably vary considerably in their pesticide concentrations.

By Randall Parker    2007 May 09 12:26 AM   Entry Permalink | Comments (9)
2007 March 18 Sunday
Shyness Gene Activates If Mother Stressed?

A professor at the University of Maryland Child Development Laboratory claims the short version of a gene involved in metabolism of neurotransmitter serotonin combined with stress creates a shy kid.

In a study published in the February issue of Current Directions in Psychological Science, Nathan Fox, professor and director of the Child Development Laboratory, and his team found that kids who are consistently shy while growing up are particularly likely to be raised by stressed-out parents, and to possess a genetic variant associated with stress sensitivity.


Like all genes, the particular serotonin-related gene examined in this study has 2 alleles, which can be long or short. The protein produced by the short form of the gene is known to predispose towards some forms of stress sensitivity.

Fox's research found that among children exposed to a mother's stress, it was only those who also inherited the short forms of the gene who showed consistently shy behavior.

"If you have two short alleles of this serotonin gene, but your mom is not stressed, you will be no more shy than your peers as a school age child," says Fox. "But we found that when stress enters the picture, the gene starts to show a strong relationship to the child's behavior," says Fox. "If you are raised in a stressful environment, and you inherit the short form of the gene, there is a higher likelihood that you will be fearful, anxious or depressed."

From this press release we do not know the sample size of his study. But his result is at least plausible.

Suppose this gene's short version works as advertised. When offspring genetic engineering becomes possible will prospective parents choose to make shyness a thing of the past? Will some future generation be anywhere between extroverted and extremely extroverted? If so, what will we lose? My guess is that governments will become more corrupt as people with genetically engineered lack of shyness feel less fear of getting held up to public condemnation.

By Randall Parker    2007 March 18 10:17 PM   Entry Permalink | Comments (1)
2007 February 18 Sunday
Higher Fish Diet Seems To Make Babies Smarter

As part of the University of Bristol Children Of The 90s project dietary information and child cognitive performance was checked for children in thousands of families (the news reports speak of 9000 families or 11,875 pregnant women - maybe the higher number includes multiple pregnancies from some of the women?) . Children whose mothers ate fish more than 3 times a week did better in tests of cognitive function.

Mothers who ate more seafood than the US guidelines (340 grams, or three portions a week) had children who were more advanced in development tests measuring fine motor, communication and social skills as toddlers, had more positive social behaviours and were less likely to have low verbal IQ scores at the age of eight. Those children whose mothers had eaten no fish were 28 per cent more likely to have poor communication skills at 18 months, 35 per cent more likely to have poor fine motor coordination at age three and a half, 44 per cent more likely to have poor social behaviour at age seven and 48 per cent more likely to have a relatively low verbal IQ at age eight, when compared with children of women who ate more than the US guidelines advised.

But did they test parental IQ? Or did they control for socio-economic status of the parents? (which would be a rough proxy for genetic differences)

Main study author Joseph Hibbeln thinks these results suggest US government advice on fish eating in pregnancy is wrong.

The new findings suggest that, for developing brains, the risks of limiting seafood consumption outweigh the benefits of such a limit, the NIH's Joseph R. Hibbeln, MD, tells WebMD.

"Regrettably, these data indicate that the [FDA-EPA] advisory apparently causes the harm that it was intended to prevent, especially with regard to verbal development," Hibbeln says.

The FDA-EPA advisory is aimed at reducing mercury exposure. But you can avoid the mercury while still getting lots of omega 3 fatty acids by either eating low mercury fish or by taking fish oil capsules.

Avoid higher mercury fish from the top of the food chain.

The study supports the contrary advice, given by the Food Standards Agency in the UK, which backs fish as a healthy food. The FSA simply advises mothers to avoid shark, swordfish and marlin, and restrict their intake of tuna.

The new research into children’s behaviour and intelligence suggests that women who follow the US “advisory” issued in 2004 to limit consumption, or cut fish out of their diet altogether, may miss nutrients that the developing brain needs — and so harm their children.

The women filled out a seafood consumption questionnaire while pregnant.

At 32 weeks into their pregnancy, the women were asked to fill in a seafood consumption questionnaire. They were subsequently sent questionnaires four times during their pregnancy, and then up to eight years after the birth of their child. Researchers examined issues including the children's social and communication skills, their hand-eye coordination, and their IQ levels. As with any study based on self-reporting methods, however, the results cannot be considered entirely definitive.

What I want to know: Did the mothers who ate less fish have lower IQs than the mothers who ate more fish? In other words, did these researchers measure an effect of nutritional differences or of genetic differences?

We still do not know with certainty that omega 3 fatty acids help make babies smarter. But since there's a chance they might it seems prudent for women to eat very low mercury fish.

High Fish Consumption Raises Baby Intelligence But Mercury Lowers IQ Also see the US FDA table Mercury Levels in Commercial Fish and Shellfish.

By Randall Parker    2007 February 18 02:20 PM   Entry Permalink | Comments (4)
2007 January 15 Monday
Abused Children Have More Inflammation As Adults

Children who were physically or sexually abused show higher levels of inflammation indicators in blood as adults.

Researchers at King's College London followed 1,000 people in New Zealand from birth to the age of 32.

A third of those who were maltreated had high levels of inflammation - an early indicator of conditions such as heart disease and diabetes.


They took blood samples to measure levels of C-reactive protein, fibrinogen and white blood cells - substances which are known to be associated with inflammation in the body.

Adult survivors of childhood maltreatment who appeared to be healthy were twice as likely to show clinically relevant levels of inflammation compared to those who had not been maltreated.

So you get abused as a kid. Bad enough. But then you go on to suffer more diseases when you get older. The suffering lasts a lifetime. How incredibly cruel.

Twenty years hence will cheap in-school testing of kids for elevated inflammation response get used to spot kids who might be getting abused at home?

Abused kids are already known to get more heart disease and other illnesses which could be caused by sustained inflammation response.

The findings could explain why children who are abused show a higher incidence of conditions such as heart disease and diabetes as adults, the researchers say. Until now, it has not been clear exactly how early stress could cause these future health problems, says Andrea Danese, a psychiatrist at King's College London in the UK.

What is the mechanism? Do the various endocrine organs become more prone to turn on the inflammatory responses? Or does brain development in the abused alter in a way that makes the brain send out stress chemicals in potentially stressful situations? I'm going to guess that the latter mechanism is at least partially responsible because abuse of children makes them more prone to violence when they get older - especially if they have the right version of the gene for the mono-amine oxidase A enzyme.

This brings up another thought: Could people who have higher levels of stress-related inflammation indicators get trained by biofeedback or other means to reduce their inflammatory response? It might not be that easy. During childhood development cells throughout the body might have gotten their epigenetic state altered to make them more prone to inflammation response.

More generally: We need better ways to dampen down inflammation responses. We have lots of responses that have ceased to be adaptive in the modern environment. Ever been in an argument at work where you felt the "fight or flight" urge? That response is a maladaptive vestige of our evolutionary history. You might some day find youself in a situation where the adrenaline rush could help you survive. But in most cases the response just makes you age more rapidly.

By Randall Parker    2007 January 15 09:54 PM   Entry Permalink | Comments (1)
2006 December 21 Thursday
Pre-Natal Fish Oil Improves Babies Hand-Eye Coordination

More evidence that omega 3 fatty acids found in fish help with the development of baby brains:

Fish oil supplements given to pregnant mums boost the hand-eye coordination of their babies as toddlers, reveals a small study published ahead of print in the Archives of Disease in Childhood (Fetal and Neonatal Edition).

The researchers base their findings on 98 pregnant women, who were either given 4g of fish oil supplements or 4g of olive oil supplements daily from 20 weeks of pregnancy until the birth of their babies.

Only non-smokers and those who did not routinely eat more than two weekly portions of fish were included in the study. Eighty three mothers completed the study.

Once the children had reached two and a half years of age, they were assessed using validated tests to measure growth and development.

These included tests of language, behaviour, practical reasoning and hand-eye coordination. In all, 72 children were assessed (33 in the fish oil group and 39 in the olive oil group).

There were no significant overall differences in language skills and growth between the two groups of children

But those whose mothers had taken fish oil supplements scored more highly on measures of receptive language (comprehension), average phrase length, and vocabulary.

And children whose mothers had taken fish oil supplements scored significantly higher in hand-eye coordination than those whose mothers had taken the olive oil supplements.

The effect might be even stronger if the mothers on the fish oil supplements breast feed. Though some baby formula contains omega 3 fatty acid DHA.

You can read the full paper as a PDF document:

Our finding of enhanced eye and hand coordination with fish oil supplementation is plausible and consistent with previously reported benefits on visual function after postnatal n-3 PUFA supplementation in both preterm14 24 and term15 25 infants. Although the underlying mechanism is not understood, DHA is known to facilitate rapid phototransduction in the retinal membrane,26 and deficiencies are associated with reduced retinal function in infant primates.2 Furthermore, effects on visual evoked potential could indicate that DHA may also have an effect on the development of the visual cortex.27 Finally, improved stereoacuity in infants has been associated with LC PUFA formula supplementation28 and fish intake of lactating mothers.29

To our knowledge, only one other study has assessed the effects of supplementation with high-dose fish oil in pregnancy on cognitive development of the offspring. A randomised clinical trial by Helland et al9 involved 590 pregnant women who received fish oil at half the dose we used in this study, from 18 weeks’ gestation until 3 months post partum. No differences in development were observed in the 269 infants tested at 6 and 9 months; however, fish oil supplementation was associated with increased mental processing in children at age 4 years. Additionally, mental processing scores were significantly correlated with maternal intake of DHA in pregnancy after adjusting for potential confounding factors10; this is consistent with observed correlations of DHA (and EPA) intake with eye and hand coordination in this study.

Other studies have found positive relationships between n- 3 PUFAs at birth (principally DHA) and aspects of visual and neurological development, in either observational studies30–32 or intervention studies using much lower levels of supplementation. 11 12 33 Our findings suggest that detection of the potentially beneficial effects of DHA in pregnancy may require larger doses. Further, although it is difficult to directly extrapolate the pregnancy dosage to supplementation of the preterm infant, the doses in our study resulted in similar increases in cord blood levels of DHA to those achieved with the higher doses trialled in preterm infants.34

The researchers acknowledge that their study was too small to prove their conclusions. But they think their conclusions are consistent with other studies of the effects of omega 3 fatty acid DHA on brain development.

Women who want to give their offspring every advantage should consider regular salmon meals or high quality omega 3 fatty acid supplements while pregnant and while lactating and breast feeding. Also, if you use baby formula and if DHA fortification is optional in your legal jurisdiction look for the formula brands that have DHA added.

By Randall Parker    2006 December 21 09:56 PM   Entry Permalink | Comments (0)
2006 September 10 Sunday
Adolescent Emotions Less Developed Than Adults

Dr Sarah-Jayne Blakemore of the University College London Institute of Cognitive Neuroscience has found from brain scans that when compared to adults kids from age 8 through the teen years use less of an area of the brain involved in empathy and emotional evaluation when making decisions about the reactions of themselves and others to future hypothetical situations.

Teenagers take less account than adults of people's feelings and, often, even fail to think about their own, according to a UCL neuroscientist. The results, presented at the BA Festival of Science today, show that teenagers hardly use the area of the brain that is involved in thinking about other people's emotions and thoughts, when considering a course of action.

Many areas of the brain alter dramatically during adolescence. One area in development well beyond the teenage years is the medial prefrontal cortex, a large region at the front of the brain associated with higher-level thinking, empathy, guilt and understanding other people's motivations. Scientists have now found that, when making decisions about what action to take, the medial prefrontal cortex is under-used by teenagers. Instead, a posterior area of the brain, involved in perceiving and imagining actions, takes over.

Kids are deficient in empathy and guilt because they haven't yet developed the brain areas needed to fully consider the effects of their actions on others.

Functional Magnetic Resonance Imaging (fMRI) brain scans done while adults and teenagers were asked the same questions showed a different pattern of brain activation in teenagers versus adults.

In the study, teenagers and adults were asked questions about the actions they would take in a given situation while their brains were being scanned using fMRI. For example, 'You are at the cinema and have trouble seeing the screen. Do you move to another seat?' A second set of questions asked what they would expect to happen as a result of a natural event eg. 'A huge tree comes crashing down in a forest. Does it make a loud noise?'

Although teenagers and adults chose similar responses, the medial pre-frontal cortex was significantly more active in adults than in teenagers when questioned about their intended actions. Teenagers, on the other hand, activated the posterior area of the brain known as the superior temporal sulcus – an area that's involved in predicting future actions based on past actions.

Adults can imagine emotional reactions more rapidly than teenagers can.

Participants aged eight to 36 years were asked how they would feel and how they would expect someone else to feel in a series of situations. Adults were far quicker than teenagers at judging emotional reactions – both how they would feel and how a third party might feel in a given situation. For example, "How would you feel if you were not allowed to go to your best friend's party?" or 'A girl has just had an argument with her best friend. How does she feel?"

Brains of kids undergo sharp growth spurts. Therefore the brain undergoes distinct stages of development.

"Whatever the reasons, it is clear that teenagers are dealing with, not only massive hormonal shifts, but also substantial neural changes. These changes do not happen gradually and steadily between the ages of 0–18. They come on in great spurts and puberty is one of the most dramatic developmental stages."

I'd like to see various types of criminals compared to a general adult population. Do some criminals lack fully developed medial prefrontal cortexes? Could neural growth hormones delivered in adolescence to juvenile delinquents steer them away from a life of crime?

Lack of brain maturity basically forces kids to use an area of the brain that makes simpler decisions based on a smaller number of considerations.

"The superior temporal sulcus is usually used in making simple actions, or watching other people make actions," said Dr Blakemore. "We think adolescents are performing this task by simply thinking about the action they're going to take.

"The part of the brain that the adults are using more is involved in much higher level thinking, such as thinking about the consequences of your actions in terms of other peoples' emotions and feelings."

Basically, adults run more complex models of the world that take into account more factors. They also experience feelings resulting from their internal mental simulations of the world and those feelings temper their actions.

Blakemore thinks the law should take into account differences in stages of brain development (and FuturePundit agrees).

The work has implications for the types of responsibility given to adolescents, Blakemore says: “Teenager’s brains are a work in progress and profoundly different from adults. If you’re making decisions about how to treat teenagers in terms of the law, you need to take this new research into account.”

Brains go through quite a transformation in the adolescent years. Kids are not just surly, sullen, rude, cruel, unhappy, and insensitive because they are sexually frustrated or resentful of their low status. Their ability to read the emotions in the faces of others even dips sharply starting around the age of 11. See my post Adolescence Is Tough On The Brain.

By Randall Parker    2006 September 10 01:40 PM   Entry Permalink | Comments (3)
2006 March 30 Thursday
Higher Intelligence Caused By Slower Brain Development

My immediate reaction is what genetic variations cause this trajectory that leads to higher intelligence?

Youth with superior IQ are distinguished by how fast the thinking part of their brains thickens and thins as they grow up, researchers at the National Institutes of Health's (NIH) National Institute of Mental Health (NIMH) have discovered. Magnetic resonance imaging (MRI) scans showed that their brain's outer mantle, or cortex, thickens more rapidly during childhood, reaching its peak later than in their peers — perhaps reflecting a longer developmental window for high-level thinking circuitry. It also thins faster during the late teens, likely due to the withering of unused neural connections as the brain streamlines its operations. Drs. Philip Shaw, Judith Rapoport, Jay Giedd and colleagues at NIMH and McGill University report on their findings in the March 30, 2006 issue of Nature.

"Studies of brains have taught us that people with higher IQs do not have larger brains. Thanks to brain imaging technology, we can now see that the difference may be in the way the brain develops," said NIH Director Elias A. Zerhouni, M.D.

Here is where political correctness enters in. Zerhouni holds a highly visible position as head of a large government research agency. So in today's intellectual environment we can't expect much from him on the topic of intelligence. There is a positive correlation between IQ and brain size. There's an even higher positive correlation between IQ and brain gray matter size. But when it comes to differences in intelligence the taboos kick in with a vengeance. See links below for the truth of the matter.

While most previous MRI studies of brain development compared data from different children at different ages, the NIMH study sought to control for individual variation in brain structure by following the same 307 children and teens, ages 5-19, as they grew up. Most were scanned two or more times, at two-year intervals. The resulting scans were divided into three equal groups and analyzed based on IQ test scores: superior (121-145), high (109-120), and average (83-108).

The researchers found that the relationship between cortex thickness and IQ varied with age, particularly in the prefrontal cortex, seat of abstract reasoning, planning, and other "executive" functions. The smartest 7-year-olds tended to start out with a relatively thinner cortex that thickened rapidly, peaking by age 11 or 12 before thinning. In their peers with average IQ, an initially thicker cortex peaked by age 8, with gradual thinning thereafter. Those in the high range showed an intermediate trajectory (see below). While the cortex was thinning in all groups by the teen years, the superior group showed the highest rates of change.

"Brainy children are not cleverer solely by virtue of having more or less gray matter at any one age," explained Rapoport. "Rather, IQ is related to the dynamics of cortex maturation."

The observed differences are consistent with findings from functional magnetic resonance imaging, showing that levels of activation in prefrontal areas correlates with IQ, note the researchers. They suggest that the prolonged thickening of prefrontal cortex in children with superior IQs might reflect an "extended critical period for development of high-level cognitive circuits." Although it's not known for certain what underlies the thinning phase, evidence suggests it likely reflects "use-it-or-lose-it" pruning of brain cells, neurons, and their connections as the brain matures and becomes more efficient during the teen years.

The development of higher intellectual abilities required longer childhoods for humans than for other primates. Therefore it is not surprising that those who are smartest have longer periods of brain development.

"People with very agile minds tend to have a very agile cortex," said Shaw. The NIMH researchers are following-up with a search for gene variants that might be linked to the newly discovered trajectories. However, Shaw notes mounting evidence suggesting that the effects of genes often depends on interactions with environmental events, so the determinants of intelligence will likely prove to be a very complex mix of nature and nurture.

I'd really like to see a massive search for the genetic variations that boost intelligence. Identification of those genetic variations will lead to identification of targets for drug development and other means for boosting IQ in children whose brains are still developing.

As for the claim above that IQ does not correlate with brain size: Studies of brain size and intelligence have found correlations around r = 0.4. One study found that after controlling for body size the correlation with brain size was 0.65. Wikipedia has a short survey of brain size and IQ research results.

Modern studies using MRI imaging shows a weak to moderate correlation between brain size and IQ (Harvey, Persaud, Ron, Baker, & Murray, 1994) and have shown that brain size correlates with IQ by a factor of approximately .40 among adults (McDaniel, 2005). In 1991, Willerman et al. used data from 40 White American university students and reported a correlation coefficient of .35. Other studies done on samples of Caucasians show similar results, with Andreasen et al (1993) determining a correlation of .38[1], while Raz et al (1993) obtained a figure of .43 and Wickett et al. (1994) obtained a figure of .40. The correlation between brain size and IQ seems to hold for comparisons between and within families (Gignac et al. 2003; Jensen 1994; Jensen & Johnson 1994). However, one study found no within family correlation (Schoenemann et al. 2000).

The brain is a metabolically expensive organ, and consumes about 25% of the body's metabolic energy. Because of this fact, although larger brains are associated with higher intelligence, smaller brains might be advantageous from an evolutionary point of view if they are equal in intelligence to larger brains. Skull size correlates with brain size, but is not necessarily indicative.

The metabolic expense of the brain is the reason why brain size positively correlates with intelligence. Calorie malnutrition has been one of the biggest causes of death of humans since humans came into existence. The cost of a larger brain is such that it will get selected against unless it provides a selective advantage. Therefore it seems unreasonable to expect no correlation between brain size and intelligence.

P. Tom Schoenemann, an anthropologist at UC Berkeley, had this to say about brain size and IQ:

More interestingly, 4 recent studies of this question for the first time derived estimates of brain size from high quality magnetic resonance imaging (MRI), instead of using external cranial dimensions. All 4 studies show much higher correlations: Willerman et al. (1991) report an estimated correlation of r = .35 (N = 40); Andreasen et al. (1993) found a correlation of r= .38 (N = 67); Raz et al (in press) found a correlation of r = .43 (N = 29); and Wickett et al. (in press) report a correlation of r = .395 (N = 40, all females). These are all statistically significant. It is quite simply a myth that brain size and IQ are empirically unrelated in modern populations.

But it is a popular myth among public intellectuals.

Also see my post Brain Gray Matter Size Correlated To Intelligence.

Update: The New York Times coverage by Nicholas Wade notes that Dr. Paul Thompson of UCLA also found in 2001 that frontal lobes gray matter volume correlates with IQ.

In 2001, Dr. Thompson reported that based on imaging twins' brains the volume of gray matter in the frontal lobes and other areas correlated with I.Q. and was heavily influenced by genetics.

Wade also reports that the team around Shaw is doing many genetic studies on intelligence and have taken genetic samples from the Bethesda children used in this study.

By Randall Parker    2006 March 30 09:14 PM   Entry Permalink | Comments (20)
2006 March 29 Wednesday
Pre-Schoolers Think Like Scientists

But the researchers do not explain what goes wrong later. Kids start out on the road to science and enlightenment.

Even preschoolers approach the world much like scientists: They are convinced that perplexing and unpredictable events can be explained, according to an MIT brain researcher's study in the April issue of Child Development.

The way kids play and explore suggests that children believe cause-and-effect relationships in the world are governed by fundamental laws rather than by mysterious forces, said Laura E. Schulz, assistant professor of cognitive science and co-author of the study "God Does Not Play Dice: Causal Determinism and Preschoolers' Causal Inferences."

"It's important to understand that kids are approaching the world with deep assumptions that affect their actions and their explanations and shape what they're able to learn next," Schulz said. "Kids' fundamental beliefs affect their learning. Their theoretical framework affects their understanding of evidence, just as it does for scientists."

Kids believe in cause and effect.

Schulz and colleague Jessica Sommerville of the University of Washington tested 144 preschoolers to look at whether children believe that causes always produce effects. If a child believes causes produce effects deterministically, then whenever causes appear to work only some of the time, children should think some necessary cause is missing or an inhibitory cause is present.

In one study, the experimenters showed children that a switch made a toy with a metal ring light up. Half the children saw the switch work all the time; half saw that the switch only lit the ring toy some of the time. The experimenters also showed the children that removing the ring stopped the toy from lighting up. The experimenters kept the switch, gave the toy to the children and asked the children to stop the toy from lighting up.

If the switch always worked, children removed the ring. If the switch only worked some of the time, children could have removed the ring but they didn't--they assumed that the experimenter had some additional sneaky way of stopping the effect. Children did something completely new: They picked up an object that had been hidden in the experimenter's hand (a squeezable keychain flashlight) and used that to try to stop the toy. That is, the children didn't just accept that the switch might work only some of the time. They looked for an explanation.

They also figured out that adults are crafty and tricky. I wonder how old they were when they figured that out.

By Randall Parker    2006 March 29 09:49 PM   Entry Permalink | Comments (9)
2006 January 23 Monday
Fish Consumption By Mom Makes Babies Smarter?

Yet another study provides evidence for the hypothesis that higher omega 3 fatty acid consumption raises IQs in babies.

Perhaps the most startling finding was that the children of those women who had consumed the smallest amounts of omega-3 fatty acids during their pregnancies had verbal IQs six points lower than average. That may not sound much, but it would have a serious effect on a country's brainpower if it were widespread. And the finding is particularly pertinent because existing dietary advice to pregnant women, at least in America, is that they should limit their consumption of seafood in order to avoid exposing their fetuses to trace amounts of brain-damaging methyl mercury. Ironically, that means they avoid one of the richest sources of omega-3s.

Dr Hibbeln, however, says his work shows that the benefits of eating such fish vastly outweigh the risks from the mercury in them. Indeed, in the Avon study, it was those children exposed to the lowest levels of methyl mercury who were at greatest risk of having low verbal IQ.

Higher omega 3 fatty acid consumption was positively correlated with better fine motor performance and negatively correlated with pathological social behavior.

One obvious question: Are smarter women more atune to popular dietary advice and hence more likely to eat fish? That could explain at least part of the results in this study. Maybe the fish eating is just a proxy for having higher IQ genes to pass on to one's children. However, other studies support the argument that omega 3 fatty acid consumption improves brain development and brain performance.

Read the whole article.

Aside: I use a margarine substitute that contains a decent amount of omega 3 fatty acids and no trans fatty acids. Keep an eye out for such products if you want to boost your omega 3 fatty acid consumption but don't want to eat fish all that often.

By Randall Parker    2006 January 23 10:07 PM   Entry Permalink | Comments (25)
2005 November 29 Tuesday
Being A Twin Costs Over 5 IQ Points

Twins pay a cognitive price.

Social and economic circumstances do not explain why twins have significantly lower IQ in childhood than single-born children, according to a study in this week's BMJ.

Researchers studied 9,832 single-born children and 236 twins born in Aberdeen, Scotland between 1950 and 1956, using a previous child development survey as a base. They also gathered further information on mother's age at delivery, birth weight, at what stage of the child's gestation they were born, their father's occupational social class, and information on other siblings.

They found that at age seven, the average IQ score for twins was 5.3 points lower than that for single-born children of the same family, and 6.0 points lower at age nine.

The study also showed that taking into account factors such as the child's sex, mother's age, and number of older siblings made little difference to the IQ gap.

Despite advances in recent years in obstetric practice and neonatal care, the authors argue that the likely explanation is because some twins have a shorter length of time in the womb than other children and are prone to impaired fetal growth.

I've been expecting this finding for years. It makes perfect sense. Mom can't feed two fetuses as well as she can feed one. I wonder if diet and perhaps exercise could at least partially compensate for this effect.

I also wonder if the use of drugs to prolong pregnancy could raise average IQ. If pregnancies could be stretched out a few extra weeks would the resulting babies grow up to be smarter? Anything that could raise average IQ a few points would do more to boost economic growth and lower social pathologies than increased educational spending or the other typical liberal or free market libertarian nostrums.

Another point: IVF therapies ought to be aimed to reduce the odds of multiple fetus pregnancies. Each baby is going to pay a steep cognitive cost from not being the sole pregnancy.

By Randall Parker    2005 November 29 10:41 PM   Entry Permalink | Comments (6)
2005 November 25 Friday
Insufficent Myelination Seen As Cause Of Mental Disorders

While decay of myelin due to auto-immune damage is suspected as a cause of multiple sclerosis some UCLA researchers see a much wider role for insufficient myelination as a cause of a large assortment of mental and behavioral disorders.

New evidence points to production of myelin, a fatty insulation coating the brain's internal wiring, as a neural Achilles' heel early in life.

An upcoming application of a novel model of human brain development and degeneration pioneered by a UCLA neuroscientist identifies disruption of myelination as a key neurobiological component behind childhood developmental disorders and addictive behaviors.

Detailed in an article in press with the upcoming annual peer-reviewed publication Adolescent Psychiatry (Hillsdale, N.J.; The Analytic Press Inc.; 2005) the analysis suggests that many factors can disrupt myelination and contribute to or worsen disorders such as autism, attention deficit/hyperactivity disorder and schizophrenia.

Note above that problems with myelination may contribute to addictive behaviors and ADHD.

There's a vicious cycle aspect to this report. Due to insufficient myelination a kid could be more prone to use of addictive drugs. But then the use of the drugs could prevent the myelination process from proceeding. This reminds me of people I know who used a lot of drugs while teenagers who never seem to have grown up since then. Did their drug and alcohol use block their own brain's maturation?

In addition, the analysis suggests that alcohol and other drugs of abuse have toxic effects on the myelination process in some adolescents, contributing to poor treatment outcomes and exacerbating co-existing psychiatric disorders.

Author Dr. George Bartzokis, a professor of neurology at UCLA's David Geffen School of Medicine, concludes that the high incidence of impulsive behaviors that characterize the teen years as well as many psychiatric disorders that occur in the teens and 20s are related to incomplete myelination of inhibitory "stop" brain circuits, while the "go" circuits become fully functional earlier in development. These inhibitory circuits are not on line to quickly interrupt high-risk behaviors that are so prevalent in teens and young adults.

If memory serves the development of the inhibitory circuits does not complete until about age 25. As a consequence of blocked myelin formation are heavy adolescent drug users more prone to impulsive, self-destructive, and violent behaviors even as adults?

There's an aging angle to myelination and demyelination.

"Myelination, a process uniquely elaborated in humans, arguably is the most important and most vulnerable process of brain development as we mature and age," said Bartzokis, who directs the UCLA Memory Disorders and Alzheimer's Disease Clinic and the Clinical Core of the UCLA Alzheimer's Disease Research Center.

"Environmental toxins, genetic predispositions and even diet appear to influence and sometimes disrupt this process," he added. "By shifting our research focus to medications that act on brain metabolism and development, as opposed to brain neurotransmitter chemistry, neuroscientists will likely find a wealth of novel opportunities for addressing the cause of brain disease rather than simply the symptoms."

Myelin is a sheet of lipid, or fat, with very high cholesterol content — the highest of any brain tissue. The high cholesterol content allows myelin to wrap tightly around axons, speeding messages through the brain by insulating these neural "wire" connections.

Bartzokis' analysis of magnetic resonance images and post-mortem tissue data suggests that the production of myelin is a key component of brain development through childhood and well into middle age, when development peaks and deterioration begins (Neurobiology of Aging, January 2004). He also identifies the midlife breakdown of myelin as a key to onset of Alzheimer's disease later in life (Archives of Neurology, March 2003; Neurobiology of Aging, August 2004).

We need rejuvenation therapies that will repair and replace aging myelin sheaths in the brain. Sign me up. I want rejuvenated myelin. Myelin rejuvenation no doubt will be part of the Strategies for Engineered Negligible Senescence (SENS) treatments.

Imagine a future two or three decades hence where parents take their kids in for cell therapies and gene therapies to make their myelin sheaths grow over their inhibitory circuitry more rapidly. Such therapies would reduce adolescent deaths from car accidents and from murder. Plus, the therapies would also reduce adolescent use of destructive drugs.

Adolescent rashness might have been selected for so that males in particular would compete more aggressively for mates. The slow myelination of inhibitory brain circuits might be an obsolete and maladaptive left-over consequence of evolution by natural selection.

By Randall Parker    2005 November 25 11:58 AM   Entry Permalink | Comments (9)
Musical Training Might Improve Brain Processing Of Speech

Trained musicians are better at detecting differences in syllable sounds.

In two Stanford studies, researchers demonstrated that people with musical experience found it easier than non-musicians to detect small differences in word syllables. They also discovered that musical training helps the brain work more efficiently in distinguishing split-second differences between rapidly changing sounds that are essential to processing language.

Nadine Gaab, a former Stanford postdoctoral fellow, will present the findings at 9:30 a.m. Nov. 16 at the Society for Neuroscience's annual meeting in Washington, D.C. "These results have important potential implications for improving speech processing in children struggling with language and reading skills," she said. They also could help "seniors experiencing a decline in their ability to pick up rapid changes in the pitch and timing of sounds, as well as speech perception and verbal memory skills, and even for people learning a second language."

But does musical training really help language skills development all that much? The problem with this study (and with most social science for that matter) is that it compares people at a snapshot point. All sorts of selection effects could be responsible for this result.

Adults with and without musical training were compared in their ability to recognize syllable sequences.

In the first study, researchers took 28 adults, divided into musicians and non-musicians, who were matched for age, gender, intelligence and general language ability. Musicians in the study were required to have started playing an instrument before the age of 7, to have never stopped playing and to have continued to play several hours a week. When musicians play, Gaab said, they must actively distinguish between sounds and their order, and adjust as necessary.

Suppose a large cohort of 7 year olds were tested for general intelligence and language skills and then some proceeded to learn music an others did not. Would the music learners be better at understanding and speaking language 20 years later? I'm skeptical.

Non-musicians in the study had to be native English speakers with minimal experience studying non-tonal foreign languages such as Spanish. People who had studied a tonal language such as Mandarin were not included.

During the experiment, participants listened to pairs of syllables such as ba-da, ba-wa and ga-ka, and noted if each syllable in the pair sounded the same or different. Depending on how they performed, the scientists made the task increasingly difficult by using syllables that sounded more and more alike. Musicians outperformed their non-musician peers in how quickly and accurately they perceived these rapid changes, Gaab said.

In the second experiment, researchers used functional magnetic resonance imaging (fMRI) to find out whether musical training changes the way the brain processes sound. The fMRI scanning machines, which look like beds that slide into tubes, normally are used to check for brain injuries or tumors. With slightly different software they can be used to measure which regions of the brain are active by looking for changes in blood oxygenation, a process that occurs in parts of the brain where the neurons are active.

Forty people, evenly divided into musicians and non-musicians, listened to three-tone sequences made from different combinations of low and high pitches. Participants had to reproduce the order of the tones they heard by manually pressing buttons on a panel.

Musicians once again beat the non-musicians with this task. "We were surprised that musicians could do it almost perfectly," Gaab said. Musicians got the fastest tone sequences right at least 85 percent of the time, compared to non-musicians who hit a 50-percent average. They also could replicate the sequences a lot faster. "Non-musicians needed to make a lot more effort—their brains were not as finely attuned."

According to Gaab, musical training appears to alter the ability of the brain's language areas to process pitch and timing changes that are common to perceiving both words and music. "The brain becomes more efficient and can process more subtle auditory cues that occur simultaneously," she said.

I see these results as analogous to how a doctor or nurse has a fingertip that is very good at measuring a pulse. The ability measured is fairly narrow. A person who learns music might be better able to distinguish syllables and words which are mumbled or spoken quietly or spoken with an acccent or under noisy conditions. The effect would be equivalent to simply having better hearing. But the benefit might be limited to just an enhanced ability to signal process sounds and may not carry over at all into enhanced ability to parse sentences and understand, say, written language.

I've long wondered how much the learning of particular skills enhance or interfere with the ability to learn other skills. For example, learning math enables the learning of physics, engineering, andd sciences because it provides a conceptual toolbox needed to understand many other subjects. But does, say, learning foreign languages use up neuons that then are unavailable for learning other subjects? Or if a person is born blind does that person have more mental resources available to learn, say, spoken languages because their mind is not cluttered by visual image information? Do parts of their brain which otherwise would have been recruited for processing images instead get recruited for better processing of sounds?

By Randall Parker    2005 November 25 10:56 AM   Entry Permalink | Comments (6)
2005 November 21 Monday
Neglected Orphanage Babies Have Lower Vasopressin And Oxytocin

Kids from Russian and Romanian orphanages have lower levels of hormones involved in bonding.

Crucial to making the link between social behavior and hormones was the work of co-author Toni Ziegler, an endocrinologist at the UW-Madison National Primate Research Center, who developed a technique that enables researchers to track vasopressin and oxytocin levels through the analysis of urine. The procedure is far less invasive than the existing method of analyzing blood or cerebrospinal fluid, and may one day find applications in several areas of child research such as the field of autism, Ziegler says.

The UW-Madison scientists worked with 18 four-year-old children who had lived in Russian and Romanian orphanages before being adopted into homes in the Milwaukee area. Despite the fact that the children now live in stable homes - for over three years, in some cases - they might still display some of the telltale behaviors that researchers have come to associate with early neglect. The abnormal willingness of a child to seek comfort from unfamiliar adults, even in the presence of the adopted parent, is one common instance of such behavior, says Wismer Fries.

Before starting her experiment, Wismer Fries collected urine samples from the young subjects to track baseline levels of vasopressin and oxytocin. Immediately, the scientists noticed that the children who experienced early neglect had markedly lower levels of vasopressin than the control group of non-adopted children. Researchers believe that vasopressin is essential for recognizing individuals in a familiar social environment. Lower levels of the hormone, Pollak says, may point to the social deprivation these children endured early on.

During the experiment, study subjects sat on the laps of either their mother or an unfamiliar woman and participated in an animated interactive computer game. The 30-minute game directed the children to engage in various types of physical contact with the adult they were sitting with, such as whispering or tickling each other, and patting each other on the head. When the game ended, Wismer Fries collected another urine sample from each child.

The UW-Madison researchers expected to see a hormonal response in the children following the physical contact with their mothers. And predictably, oxytocin levels rose in family-reared subjects. Yet, levels stayed the same among the previously neglected group. That result may help explain the difficulties many of these children have in forming secure relationships, the UW-Madison scientists say.

An obvious long term question needs answering: Do oxytocin and vasopressin levels of neglected kids eventually converge with levels found in normal kids of the neglected kids are adopted into stable homes? What happens after 10 or 15 years? Are these kids permanently tweaked?

By Randall Parker    2005 November 21 10:16 PM   Entry Permalink | Comments (8)
2005 November 20 Sunday
Give Sleeping Drugs To Adolescents?

The New York Times has an interesting article on the appropriateness of sleep aid drugs for adolescents.

Because teenagers are more likely to have trouble falling asleep than staying asleep all night, shorter-acting drugs, like Sonata and Ambien, may be more appropriate for them than Lunesta, which is longer-lasting, the specialists say.

Rozerem, an insomnia medication just approved by the F.D.A. in July for use in adults, may have an even more selective effect on the brain.

It is directed at receptors in the suprachiasmatic nucleus, which sets the body's internal clock.

And because this clock is thought to shift adolescents' sleep patterns, some doctors suspect that Rozerem may be useful in treating their sleep problems.

Since adolescents tend to stay up later and get up later why not just shift schools to later hours to make school hours fit the natural body rhythms of adolescents? To say that adolescents have sleep problems implies a medical condition like an illness. But we do not know why so many adolescents operate on later sleep cycles. Their behavior might be the result of Darwinian natural selection for effective mating strategies. Or their minds might respond more to light stimuli and artificial lighting might be shifting their melatonin production to make them stay out later. Or perhaps adolescent brains develop better if they can spend part of their days in lower light conditions and hence natural selection produced this behavior to improve brain development.

I'm speculating. But my point is that we do not know what causes adolescent sleeping patterns. Therefore efforts to pharmaceutically interfere with natural sleep cycles in order to make adolescents fit in better in institutions shaped for adult convenience seem ill advised. Such interference might produce unforeseeable and harmful consequences on brain development or other aspects of the body's growth.

Perhaps the use of high intensity lights to shift adolescent sleep patterns would be a less risky alternative. If the adolescent brain's sleep regulating mechanism can be fooled into thinking the day starts earlier and ends earlier then it might be able to function just fine on earlier real clock times.

But, again, why not just shift school schedules a couple of hours? Start schools at 10 AM or 11 AM. The kids sitting like zombies in classes at 8 AM aren't learning as much as they could learn at later hours in the day. Teachers could handle teaching till 5 PM rather than 3 PM in the afternoon. Institutions should be molded around human biology rather than the other way around. Or instead of listening to so many hours of live lectures in the morning when so many kids are half asleep the kids could watch more high resolution recorded lectures in the evenings when their minds are sharp. We can use technology to adjust institutions to humans. Why not do it?

By Randall Parker    2005 November 20 12:42 PM   Entry Permalink | Comments (15)
2005 October 06 Thursday
Tallness In Women Correlates With Masculine Ambitions

Taller women are more ambitious.

Scots academics questioned 1,220 women from the UK, United States, Canada and Australia and found the taller ones were less broody, had fewer children and were more ambitious. They were also likely to have their first child at a later age.

Shorter women tended to be more maternal and homely, according to research carried out by psychologists Denis Deady, of Stirling University, and Miriam Law Smith, from St Andrews University.

The researchers theorize that higher testosterone made the women taller while simultaneously causing their brains to develop to have more masculine features.

They conclude, rather, that taller women have more of the male sex hormone testosterone, which could give them more “male” traits, such as being assertive, competitive and ambitious.

This is a plausible hypothesis. But note they have not done any biological testing. Such studies are orders of magnitude more expensive. Also, testosterone might be higher in taller women only during development and testing adult women might not catch the higher testosterone.

It would be interesting to know whether homosexual women are taller than heterosexual women on average.

Also, adjusted for IQ are taller women more likely to commit crimes than shorter women? One would expect greater masculinity to correlate with higher crime rates, all else equal.

Also, do taller women have a higher ratio of mathematical and spatial reasoning aptitudes to verbal aptitudes as compared to shorter women?

Taller women are driven less by the desire to have children and more by the desire to succeed in a career.

Ms Law Smith, 27, who is 5ft 7in and has no children, said: "We related the height of every woman with their scores. It wasn't so much that women above a certain height were less maternal . . . more that the taller she was the less maternally driven she was likely to be.

I also wonder whether particular types of diets during development cause changes in the relative ratios of sex hormones. For example, would a high protein versus high fat versus high carbohydrates diet cause small but significant differences in the absolute levels and relative ratios of androgen hormones during development? Or would higher saturated fat versus less saturated fat cause differences in absolute and relative androgen levels? Or how about omega 3 versus omega 6 ratios?

In the longer run will society become more masculine? Will people use offspring genetic engineering techniques to make their daughters slightly more masculine in order to make them more ambitious to pursue careers? Will they make sure all their sons are not wimps? Will most countries become societies of alpha personalities and much higher levels of competition?

By Randall Parker    2005 October 06 11:17 AM   Entry Permalink | Comments (28)
2005 August 15 Monday
Moderate Prenatal Alcohol Exposure Slows Down Baby Brains

Moderate prenatal alcohol exposure too low to cause recognizable Fetal Alcohol Syndrome makes the brains of the resulting children less able to carry out complex tasks.

  • Prenatal alcohol exposure is often linked to slower cognitive reaction times and poorer attention.
  • A new study investigates cognitive function and speed as tasks become more complex.
  • Findings indicate that alcohol-exposed children can perform as well as other children on simple tasks, but as tasks become more demanding and challenging, processing speed slows down significantly.

As the kids grow up they are unable to advance to learning the increasingly complex tasks necessary for advanced education and intellectually complex occupations.

Decades of research have left little doubt that prenatal alcohol exposure has adverse effects on intellectual and neurobehavioral development. A recent study of the effects of moderate to heavy prenatal alcohol exposure on cognitive function confirms earlier findings of slower processing speed and efficiency, particularly when cognitive tasks involve working memory. Results are published in the August issue of Alcoholism: Clinical & Experimental Research.

"Prenatal alcohol exposure is often associated with slower reaction times and poorer attention in infancy, and some of these deficits may be at the core of poorer academic performance and behavior problems often seen later in childhood," said Matthew J. Burden, postdoctoral research fellow at Wayne State University School of Medicine and corresponding author for the study. "In cases of fetal alcohol syndrome (FAS) … lower IQ scores are common, often reaching the level of mental retardation. This is because alcohol consumed by the mother has a direct impact on the brain of the fetus. However, full FAS is not required to see this impact; it is just less obvious to detect across the array of exposures found in fetal alcohol spectrum disorders (FASD), which include effects of prenatal alcohol at lower drinking levels."

Julie Croxford, graduate research assistant at Wayne State University, says there is a need for researchers to look at the damage caused by prenatal alcohol exposure at lower-than-heavy levels of drinking. "In the past, much focus was placed on studying the full-blown FAS," she said. "More recent research has considered those individuals damaged by lower levels of exposure. This is an important focus."

For this study, researchers assessed 337 African-American children (197 males, 140 females) at 7.5 years of age; selected from the Detroit Prenatal Alcohol Longitudinal Cohort, the children were known to have been prenatally exposed to moderate-to-heavy levels of alcohol. Their mothers were originally recruited between September 1986 and April 1989 during their first prenatal visit to a maternity hospital clinic. The children were assessed on processing speed and efficiency in four domains of cognitive function – short-term memory scanning, mental rotation, number comparison, and arrow-discrimination processing – using a Sternberg paradigm, which examines speed of completion as problems become increasingly more difficult.

"We chose these four domains because they allow us to study distinct aspects of cognition within the same cognitive framework," said Burden. "This helps to distinguish potentially specific deficits from those that are more global in nature; that way we get a better understanding of how prenatal alcohol exposure affects cognitive functioning many years later in childhood. We used the Sternberg paradigm because it indicates how fast an individual generates the correct response to a number of problems, providing an overall measure of speed; and it examines the rate at which response times increase as problem difficulty increases, providing a processing efficiency measure."

Although the alcohol-exposed children were able to perform as well as the other children when tasks were simple – such as naming colors within a timed period – when pressed to respond quickly while having to think about the response, their processing speed slowed down significantly.

"This suggests that processing speed deficits are more likely to occur within the context of some cognitive demand," said Burden. "We also found that prenatal alcohol exposure was associated with poorer efficiency on number processing, a finding consistent with past research showing more specific adverse effects in the arithmetic domain. Arithmetic performance may be relatively more compromised with prenatal alcohol exposure than other types of intellectual performance, such as verbal abilities. We also looked at how processing speed related to other aspects of cognition, working memory in particular. Prenatal alcohol exposure had some impact on both speed and working memory, but the effect on working memory was partly accounted for by the deficits in speed – in other words, slower performance contributes in part to poorer working memory."

"The conclusion drawn here is that the reaction-time deficits associated with prenatal alcohol exposure are seen more in demanding/challenging cognitive tasks that involve the integration of working memory," said Croxford. "The real-world implications of this are that children exposed prenatally to alcohol may be able to perform simple tasks, but may struggle with tasks that are more challenging and require complex cognition and the use of working memory. This is likely to mean that these children may be more and more challenged the older they get by the demands placed on them within the school system and within their day-to-day social interactions."

Researchers controlled for many other variables and still found the effect.

Both Burden and Croxford noted that this study also examined the impact of "confounding" factors such as home environment, socioeconomic status, and current maternal drinking levels, which researchers believe may contribute to the poor outcomes seen in children exposed to prenatal alcohol.

"In this study, we accounted for more than 20 of these potentially confounding influences in the analyses," said Burden. "The effect of alcohol exposure in utero persisted above and beyond any other influences present."

What this means, said Croxford, is that alcohol itself causes specific, identifiable and permanent deficits in brain development and physiology. "This reinforces the current public health message that women should not drink alcohol during pregnancy," she said.

Burden said that he and his colleagues will continue to examine the long-term effects of prenatal alcohol exposure on the same children. "In addition to neuropsychological and behavioral measures, we will also be using electrophysiological techniques such as event-related potentials and neuroimaging (fMRI) to more directly connect cognitive performance with brain function," he said.

Look ahead 20 years. Imagine that implantable nanosensors can detect and record a pregnant mother's alcohol consumption. She could be checked periodically by passing a reading device over her body to read the records of her embedded nanosensors. If she has consumed alcohol or taken harmful drugs or smoked cigarettes or eaten food that contains toxins all this could be detected.

Well, assuming that becomes possible do you suppose some governments in more industrialized countries might require all pregnant women to have nanosensors implanted in them? The argument for why this would beneift society is easy to make. Why should pregnant women have a legal right to harm the cognitive development of their fetuses? The rest of us suffer the consequences (lower academic achievement, lower earnings, lower taxes paid, more state aid received, more behavioral problems, and probably more crime) if women do harm to their developing fetuses. So why shouldn't the fetuses be protected from avoidable harm by use of state powers?

As I see it the more we can measure ways that people harm each other (e.g. pollution or drug abuse while pregnant or while nursing or by child abuse) the more ways we should intervene to stop that harm. Now, an obvious argument to make is that fetuses are not yet legal humans and therefore do not have rights to protect. Even if one accepts the moral argument (and many don't) I still see a utilitarian argument for protecting fetuses from damage since we all benefit. I also see a rights-based argument: Fetuses that are not cognitively impaired by drug and alcohol exposure are less likely to develop into adults who have behavioral problems that cause them to violate the rights of others.

Update: Before anyone tells me that they can't imagine their government imposing fetal nanosensor monitors on women keep in mind that there are nearly 200 national governments in the world and most of them are not Western and not liberal. China has the biggest population in the world (though India will likely eventually surpass it by mid 21st century) and China imposes a One Child policy on its entire population. China is on course to become the largest economy in the world. Other East Asian countries similarly do not share Western conceptions of the proper role of government.

By Randall Parker    2005 August 15 05:08 PM   Entry Permalink | Comments (26)
2005 June 23 Thursday
High Fish Consumption Raises Baby Intelligence But Mercury Lowers IQ

A study of 135 Boston area babies has found that mercury from fish lowers baby IQ but low mercury fish consumption raises baby IQ dramatically. (same article here and here and here)

The women in the study ate fish on average once a week during the second trimester of their pregnancy. The highest intelligence scores were among the babies whose mothers had consumed more than two helpings of fish per week but whose mercury levels remained under 1.2 parts per million, according to the report published online last month in the journal Environmental Health Perspectives.

For each additional weekly serving of fish, the babies' intelligence scores increased by 4 points, or an average of almost 7%. But for every increase of 1 part per million of mercury, the babies' intelligence scores dropped by 7.5 points, or 12.5%. A woman could raise her mercury level by 1 ppm if she ate an average-sized serving of swordfish once a week, said Dr. Emily Oken of Harvard Medical School, the study's lead researcher.

"The range of fish intake in our study was from zero to 5.5 servings per week, so these were not women who were eating fish daily or multiple times a day," said Oken, who specializes in pregnancy and nutrition.

The beneficial effects of the fish consumption is almost certainly coming from the omega 3 fatty acids in the fish. A reduction in mercury exposure combined with an increased consumption of omega 3 fatty acids could produce a large increase in average intelligence in future generations. The resulting increase in the smart fraction of the population would lead to a large increase in economic output and living standards.

The full paper is not on the web at the time I'm typing this but the paper "Maternal Fish Consumption, Hair Mercury, and Infant Cognition in a US Cohort" will be free to view at this link when it gets put on the web.

While poking around trying to find the previous paper I came across another recent research paper on the Environmental Health Perspectives web site about the economic costs of mercury due to lowered IQs.

Methyl mercury is a developmental neurotoxicant. Exposure results principally from consumption by pregnant women of seafood contaminated by mercury from anthropogenic (70%) and natural (30%) sources. Throughout the 1990s, the U.S. Environmental Protection Agency (EPA) made steady progress in reducing mercury emissions from anthropogenic sources, especially from power plants, which account for 41% of anthropogenic emissions. However, the U.S. EPA recently proposed to slow this progress, citing high costs of pollution abatement. To put into perspective the costs of controlling emissions from American power plants, we have estimated the economic costs of methyl mercury toxicity attributable to mercury from these plants. We used an environmentally attributable fraction model and limited our analysis to the neurodevelopmental impacts--specifically loss of intelligence. Using national blood mercury prevalence data from the Centers for Disease Control and Prevention, we found that between 316,588 and 637,233 children each year have cord blood mercury levels > 5.8 µg/L, a level associated with loss of IQ. The resulting loss of intelligence causes diminished economic productivity that persists over the entire lifetime of these children. This lost productivity is the major cost of methyl mercury toxicity, and it amounts to $8.7 billion annually (range, $2.2-43.8 billion; all costs are in 2000 US$). Of this total, $1.3 billion (range, $0.1-6.5 billion) each year is attributable to mercury emissions from American power plants. This significant toll threatens the economic health and security of the United States and should be considered in the debate on mercury pollution controls.

If the new Boston babies study is correct then the economic costs of mercury pollution might be even higher than this latter paper assumes. Therefore the lax and slow approach of the Bush Administration (and, to be fair, the Clinton Administration and other Administrations before it) toward reduction of mercury emissions is even more short-sighted and stupid than I already thought it was. FuturePundit gets angry thinking about the coal burning electric plants emitting mercury and the less noticed (and possibly worse - see below) chlorine plants that do the same.

Marla Cone of the LA Times who wrote the first article I linked to above also wrote a previous article on mercury emissions from coal burning electric plants and chlorine plants and how chlorine plants might be worse than coal plants for mercury emissions.. (same article here and here)

In 2000, 11 chlorine plants reported releasing 14 tons of mercury into the air through smokestacks and unmonitored leaks called "fugitive" emissions. But according to the EPA, another 65 tons of mercury were used there and unaccounted for.

EPA officials, in a 2003 report, said "that the fate of all the mercury consumed" at the chlorine plants "remains somewhat of an enigma."

If even half of that "lost" mercury were released into the air, the plants would have polluted the air with nearly the same volume as the 49 tons released by the nation's 497 mercury-releasing power plants that year, said Oceana's pollution campaign director, Jackie Savitz.

By 2002, two of the 11 plants had closed, and the reported mercury emissions dropped almost in half, to a total of 7.6 tons. The plants, however, had 28 tons of mercury that were unaccounted for, which amounted to about 1% of their total mercury used and stored, according to a 20

An enigma? Are they serious?

Where is all the chlorine plant mercury going? Probably into the atmosphere.

In a lawsuit filed today by NRDC (Natural Resources Defense Council) and Sierra Club, represented by Earthjustice, the groups charge that the rule, issued in December, does not address "lost" mercury pollution from the plants and eliminates prior pollution control requirements. In a parallel legal document, the NRDC today petitioned EPA to reconsider its December rule, and set standards that will guarantee reductions in toxic mercury emissions.

Just nine mercury cell chlorine plants are still in operation in the United States. This handful of plants purchases dozens of tons of mercury each year, to replace mercury that evaporates from the giant vats they use to make chlorine. Each plant has more than 50 of these mercury vats (called "cells" in the industry) measuring approximately 50 feet long by more than five feet wide, and each cell holds some 8,000 pounds of mercury each. In 2000 these plants purchased 65 tons of replacement mercury; in 2002, 130 tons.

"The amount of mercury that these plants are losing' dwarfs the estimated 43 tons of mercury emitted by coal-fired power plants, and it's all disappearing from nine outdated factories," said Earthjustice attorney Jim Pew, who is representing the groups in their lawsuit.

The EPA publicly acknowledges that it has not accounted for the tons of mercury that each plant must replace every year. The agency concluded in its December rule that "the fate of all the mercury consumed at mercury cell chlor-alkali plants remains somewhat of an enigma."

"It's outrageous that the EPA has no apparent interest in discovering what happens to 65 tons of mercury, which these plants likely emit into the air, and plans to do nothing about it," said Jon Devine, an NRDC attorney. "The agency apparently has forgotten what its name stands for."

The EPA and FDA advise pregnant women against consumption of high mercury fish.

Do not eat Shark, Swordfish, King Mackerel, or Tilefish because they contain high levels of mercury.

The US Environmental Protection Agency (EPA) and US Food and Drug Administration (FDA) have a table of mercury levels in fish in parts per million (PPM) which you all ought to go take a look at. Look for the ones which are really low in mercury and eat them. Parenthetically, another study provides evidence that mercury might be even higher in some fish than the previous table shows. This study sampled fish purchased in New Jersey (which was not all from New Jersey) and found higher mercury levels than the older FDA/EPA table shows.

To compare actual mercury measures against data reported by the FDA, the team purchased and assayed samples of six additional types of fish (Chilean sea bass, porgy, red snapper, croaker, cod, and whiting) and two types of shellfish (shrimp and scallops) from central New Jersey markets. These species were chosen because of their wide availability in the state.

Mean levels of mercury were higher in the sea bass, croaker, whiting, and shrimp available in New Jersey--as well as the tuna sampled in the first tier of the study--than predicted by the FDA's data; the actual mean for one fish, croaker, was nearly three times the FDA estimate. The authors say these discrepancies show that the FDA should update its database (the data provided were collected mainly from 1990 to 1992). They also suggest that the agency consider providing regional breakdowns of aggregate mercury levels so state agencies can evaluate possible risks for their citizens.

What I'd like to see: A table that takes the amount of omega 3 fatty acids in fish and the amount of mercury and then ranks fish according to the ratio of omega 3 fatty acids to mercury. In other words, how to get the most amount of omega 3 fatty acids to mercury? Not all fish have as much omega 3 fatty acids. Salmon is one of the better fish for omega 3's. It also happens to be very low in mercury. So salmon is my preferred fish.

Higher consumption of low mercury fish will also lead to fewer heart attacks and less heart failure.

(BETHESDA, MD)—Older people who ate fish once or twice a week had a 20 percent lower risk of developing congestive heart failure during 12 years of follow-up, according to a new study in the June 21, 2005, issue of the Journal of the American College of Cardiology.

This is the first study to look at fish intake and the development of heart failure.

“Prior studies have shown fish intake to be associated with lower risk of fatal heart attacks. The results of the present study suggest that intake of fatty fish — high in omega-3 fatty acids — may reduce the risk of developing heart failure as well,” Dr. Mozaffarian added.

From 1989 to 1990, the researchers gave diet questionnaires to 4,738 adults in four cities who were 65 or older and free of congestive heart failure. During 12 years of follow-up, 955 participants developed congestive heart failure. After adjusting the results for other risk factors, those who had reported that they ate tuna or other fish once or twice a week were 20 percent less likely to develop congestive heart failure than those who said they ate such fish less than once a month. Eating fish three or four times a week was linked to a 31 percent lower risk of developing congestive heart failure over the next 12 years. However, fried fish consumption was linked to a higher risk of congestive heart failure.

Update: Since the world's fisheries are becoming depleted and many fish have problems with either mercury or organic toxins or both what we really need is genetic engineering of food crops such as soy, corn, and wheat to make them synthesize large amounts of the omega 3 fatty acids docosahexaenoic acid (DHA) and Eicosapentaenoic Acid (EPA). We need large cheap terrestrial sources of the omega 3 fatty acids. The alpha linolenic fatty acid (ALA) in flax seed is less than ideal and we'd be better off with a food crop that directly produced DHA and EPA.

By Randall Parker    2005 June 23 12:37 PM   Entry Permalink | Comments (42)
2005 May 19 Thursday
School Expulsion Rates Highest For 4 Year Olds

With support from the Foundation for Child Development the Yale Child Study Center has released a study on the high expulsion rates of poorly behaved 3 and 4 year olds from preschool programs.

New Haven, Conn. — Pre-K students are expelled at a rate more than three times that children in grades K-12, according to a primary study by researchers at Yale on the rate of expulsion in prekindergarten programs serving three- and four-year-olds.

Led by Yale Child Study Center researcher Walter S. Gilliam, the study, titled “Prekindergartners Left Behind: Expulsion Rates in State Prekindergarten Systems,” is based on data gathered in the National Prekindergarten Study (NPS). The paper reports on expulsion rates by program setting (public school, Head Start, private providers), gender, and race/ethnicity. The pre-K report also presents expulsion data from all 40 states that fund prekindergarten programs.

The study found that although rates of expulsion vary widely among the 40 states funding prekindergarten, state expulsion rates for prekindergartners exceed those in K-12 classes in all but three states. Prekindergarten expulsion rates vary by classroom setting. Expulsion rates are lowest in classrooms located in public schools and Head Start, and highest in faith-affiliated centers, for-profit childcare and other community-based settings. In classrooms where the teacher had no access to a psychologist or psychiatrist, students were expelled about twice as frequently. The likelihood of expulsion decreases significantly with access to classroom-based behavioral consultants that provide teachers with assistance in behavior management.

“No one wants to hear about three- and four-year-olds being expelled from preschool, but it happens rather frequently,” said Gilliam. “Pre-K teachers need access to the support staff they need to help manage classroom behavior problems. Without this support, we are setting up for failure both our children and their teachers.”

The study found that four-year-olds were expelled at a rate about 1.5 times greater than three-year-olds. Boys were expelled at a rate over 4.5 times that of girls. African-Americans attending state- funded prekindergarten were about twice as likely to be expelled as Latino and Caucasian children, and over five times as likely to be expelled as Asian-American children.

“Classroom-based behavioral consultation appears to be a promising method for reducing prekindergarten expulsion,” said Gilliam. “When teachers reported having access to a behavioral consultant who was able to provide classroom-based strategies for dealing with challenging student behaviors, the likelihood of expulsion was nearly cut in half.”

This is yet another extension of stereotypical liberal-left politically correct whining about inequality. Even preschoolers are not free from the forces of politically correctness. Bad boys are relabelled "challenging". We are all collectively turning our backs on yet another source of horrible inequity ("No one wants to hear about..."). The implication here is that boisterous out-of-control preschoolers are somehow getting discriminated against. Little boys are victimized by expulsions (never mind that they beat each other up more than little girls do). Some racial minorities are victimized while others (Asians) get even better treatment than whites. What's next? Calls for a "No Preschoolers Left Behind" legislation to complement the ridiculous No Child Left Behind law? Plus, there is the predictable claim that more experts are needed to handle the problem. Picture me rolling my eyes.

But let me stop ranting and tell you what is interesting and unsurprising about this result. Toddlers are known to be violent and uninhibited. In case you missed it go read my previous post "Humans Most Violent When Only 2 Years Old". We should expect 3 and 4 year olds to get into more trouble with "the law" than, say, 7 or 10 year olds. Why? Toddler brains are less well developed and their inhibitions against violence in particular are just not wired up yet. They try to dole out lots of physical violence. We tend not to notice this so much because most interactions that 3 year olds have are with adults and a 3 year old can't inflict much in the way of physical damage on adults. So their attempts to punch just seem cute and lame. But expect trouble if you put a bunch of them together where they can pick on someone their own size.

Fortunately toddlers are too uncoordinated and weak to do serious damage. But some of them will cause enough disruptions to make keeping them in groups with lots of others highly problematic. Attempts by "experts" to keep the more disruptive ones in groups with the better behaved seem misguided.

Also see my post "Adolescence Is Tough On The Brain". Note that the part of the brain that inhibits risky behavior does not fully develop until age 25.

Thanks to Raj for the tip.

By Randall Parker    2005 May 19 10:44 AM   Entry Permalink | Comments (16)
2005 May 18 Wednesday
Baby Cry Analysis Detects Neurological Problems

Qualities of a baby's cry can point to a number of neurological problems.

In a research review in the current issue of Mental Retardation and Developmental Disabilities, Linda LaGasse, PhD, and Barry Lester, PhD, with the Bradley Hasbro Children's Research Center (BHCRC) and Brown Medical School looked at previous studies that analyzed the acoustics of a baby's cry. The authors cite the characteristics of a cry that can indicate problems in a baby's nervous system, as well as sudden infant death syndrome (SIDS).

Changes in frequency, amplitude, length of cries, and resonance provide useful information for detecting diseases and disorders.

Overall, studies have repeatedly shown that infants at medical risk (like premature babies), and infants who have been exposed to lead or drugs, cry at a higher and more variable frequency than normal, but at lower amplitude, and with short utterances. These types of cry signals point toward a capacity problem in the respiratory system as well as an increased tension and instability of neural control of the vocal tract.

High resonance combined with mode changes indicate greater risk of Sudden Infant Death Syndrome.

These results cry out for practical application. Some sound analysis software developed for a personal computer combined with a microphone plugged into a computer port would let mom check out her baby's cries for risk factors.

If the sound of a baby's cry has diagnostic value then might the same be true for the sound of an adult's conversational voice or an adult's singing voice or perhaps for a scream made to check voice quality?

This result reminds me of recent reports on the uses of saliva and breath for disease diagnosis. The development of less invasive means of testing for diseases will allow humans to be continually monitored for disease indicators without the risk of x-ray exposure, trips to doctors' offices to get blood samples, or other more invasive, time consuming, expensive, and risky methods of testing.

By Randall Parker    2005 May 18 05:57 AM   Entry Permalink | Comments (4)
2004 December 12 Sunday
Lesbianism May Be Increased By Thyroxine And Amphetamine In Pregnancy

Professor Lee Ellis and colleages at Minot State University N.D. have found that mothers of homosexual daughters used thyroxine and amphetamine in pregnancy at higher frequencies than mothers of heterosexual daughters.

The researchers found that the mothers of homosexual women were at least five times more likely to have taken synthetic thyroid medications during pregnancy than mothers of heterosexual women, and eight times more likely to have used amphetamine-based diet pills such as Dexedrine and diethylpropion.

They also found evidence that some drugs have the opposite effect during pregnancy, reducing the probability of homosexual offspring. Mothers of heterosexual males were 70 per cent more likely to have taken drugs to combat nausea than those of male homosexuals.

The effect of the drug use is most pronounced in the first trimester of pregnancy. Since it is generally believed that sexual orientation of the brain is set during the first trimester this aspect of the result is not surprising and it can even be seen as strengthening the likelihood that this result will hold up when a follow-up study is conducted on a larger number of subjects.

I predict that in the future as the influence of various drugs on sexual orientation become known women will intentionally use drugs to increase the odds that their children will be born with the sexual orientation that they prefer. Will lesbian women use sexual selection techniques to ensure that their offspring will be daughters? Also, will they choose to have lesbian or heterosexual daughters?

Since women are the one that carry babies in pregnancy and hence (at least in Western societies) women have a bigger say on what goes on in their bodies during pregnancy my guess is that female homosexuality will be selected for more often than male homosexuality will be selected for. I expect male homosexuality to become more rare once means to decrease its likelihood are identified. I am not sure whether female homosexuality will become more or less common. My guess is it will become less common as well.

For other work by Lee Ellis see my post Obesity Being Selected For In Modern Society?

Update: Given that amphetamines and synthetic thyroid hormone are products of mid 20th century industrial civilization this result strongly suggests that industrial civilization has caused a higher incidence of lesbianism.

What else has industrial civilization done to alter, on average, human biological development? Certainly drug abuse and alcohol abuse cause an increase in the incidence of an assortment of defects. Medicine is allowing more defective babies to survive pregnancy and early childhood. Medicine, public health measures (e.g. sterile water) and higher living standards (more food, better shelter) are also reducing the selective pressure caused by infectious diseases. What is that causing to be selected for instead? Chemical pollutants might be causing other changes that influence fertility, cognitive ability, behavior, and degree of masculinity and femininity.

There are two issues that need to be separated here: First, how are elements of modern environments (e.g. specific drugs, quantity and quality of food) altering development of individuals as reported above? Second, what changes in natural selective pressure are happening as a result of these changes and what genetic variations are being selected for or against? Both of those questions will get many more answers in the years ahead.

One point can be made about the above case: If being a lesbian reduces fertility (anyone know?) then any genetic variant that increases the likelihood that one will take amphetamines or thyroid hormone is (probably very slowly) being selected against. Also, any genetic variant which makes it more likely that a female fetus will become homsexual in response to amphetamine exposure or thyroid hormone exposure is also (again, probably very slowly) being selected against.

By Randall Parker    2004 December 12 02:21 AM   Entry Permalink | Comments (5)
2004 November 11 Thursday
Poor Nutrition In Early Postnatal Years Leads To Antisocial Behavior

A study on nutrition and behavior in the Indian Ocean island of Mauritius has implications for more developed countries.

Malnutrition in the first few years of life leads to antisocial and aggressive behavior throughout childhood and late adolescence, according to a new University of Southern California study.

"These are the first findings to show that malnutrition in the early postnatal years is associated with behavior problems through age 17," said Jianghong Liu, a postdoctoral fellow with USC's Social Science Research Institute and the lead author of the study published in the American Journal of Psychiatry's November issue.

"Identifying the early risk factors for this behavior in childhood and adolescence is an important first step for developing successful prevention programs for adult violence," she said.

For 14 years, researchers followed the nutritional, behavioral and cognitive development of more than 1,000 children who lived on Mauritius, an island in the Indian Ocean off the coast of Africa.

The sample of boys and girls included children with Indian, Creole, Chinese, English and French ethnicities.

Researchers assessed their nutrition at age 3, looking for four indicators in particular:

  • angular stomatitis, or cracking in the lips and corners of the mouth that is caused by a deficiency of the B vitamin riboflavin;
  • hair dyspigmentation, a condition – found primarily in tropical regions – where children's hair takes on a reddish-orange color due to protein deficiency;
  • sparse, thin hair created by a deficiency in protein, zinc and iron; and
  • anemia, which reflects iron deficiency.

The children's intelligence level and cognitive ability were also tested, and social workers visited their homes to come up with a so-called adversity score that summarized factors such as the income, occupation, health, age and education levels of their parents and their overall living conditions.

At ages 8, 11 and 17 years, the researchers looked at how the children were behaving in school and at home.

At age 8, teachers gave feedback about whether the subjects were acting out in school with behavior ranging from irritability to picking fights with other children.

At age 11, the feedback came from parents who told researchers about whether their children lied, cheated, got into fights, bullied others, destroyed property or used obscene language.

At age 17, both parents and teachers reported on antisocial behavior such as stealing, drug use, destroying property or being deliberately cruel to others.

Over time, a link became evident between malnourishment and antisocial or aggressive behavior, said Adrian Raine, a co-author of the study and holder of the Robert Grandford Wright Professorship in Psychology in USC's College of Letters, Arts and Sciences.

Compared to those in the control group – the group that did not suffer from nutritional deficiencies – malnourished children showed a 41 percent increase in aggression at age 8, a 10 percent increase in aggression and delinquency at age 11 and a 51 percent increase in violent and antisocial behavior at age 17.

While social class did not play a significant factor in behavior, intelligence level did, Raine said.

"Poor nutrition, characterized by zinc, iron, vitamin B and protein deficiencies, leads to low IQ, which leads to later antisocial behavior," he said. "These are all nutrients linked to brain development."

Researchers also found that the more indicators of malnutrition there were, the greater the antisocial behavior.

The findings have implications for the United States, Raine said, where 7 percent of toddlers suffer from iron deficiency, a number that jumps to between 9 percent and 16 percent in adolescent and female groups.

Iron deficiency is between 19 percent and 22 percent in black and Mexican American females, he said.

"This is a problem in America. It's not just a problem in the far-away Indian Ocean," Raine said. "If it's causal, there's an intervention implication there. At a societal level, should parents be thinking more about what kids are eating?"

Of course to make use of this information in America we'd have to at least implicitly acknowledge that there are group differences in behavior that have biological causes rather than social causes. Whether biological origins or genetic or nutritional or some other factor (e.g. pathogens, pollutants) that sort of thinking is taboo among most academics, reporters, and political activists.

Raine has previously reported that protein and omega 3 fatty acid supplementation of diets of poor children in Mauritius decreased their level of criminal activity when they got older.

Raine has done a lot of other interesting work on the biological mind and the biological roots of behavior. For example, see my post Brain Scans Show Abnormalities In Psychopaths.

By Randall Parker    2004 November 11 03:16 PM   Entry Permalink | Comments (1)
2004 November 05 Friday
IQ Lower In Babies Who Engage In Prolonged Crying

A team at the US National Institues of Health working with researchers in Norway has found that babies who cry for a long time turned out at age 5 to have much lower IQs than the control group.

BACKGROUND: Long term studies of cognitive development and colic have not differentiated between typical colic and prolonged crying. OBJECTIVE: To evaluate whether colic and excessive crying that persists beyond 3 months is associated with adverse cognitive development. DESIGN: Prospective cohort study. A sample of 561 women was enrolled in the second trimester of pregnancy. Colic and prolonged crying were based on crying behaviour assessed at 6 and 13 weeks. Children's intelligence, motor abilities, and behaviour were measured at 5 years (n = 327). Known risk factors for cognitive impairment were ascertained prenatally, after birth, at 6 and 13 weeks, at 6, 9, and 13 months, and at 5 years of age. RESULTS: Children with prolonged crying (but not those with colic only) had an adjusted mean IQ that was 9 points lower than the control group. Their performance and verbal IQ scores were 9.2 and 6.7 points lower than the control group, respectively. The prolonged crying group also had significantly poorer fine motor abilities compared with the control group. Colic had no effect on cognitive development. CONCLUSIONS: Excessive, uncontrolled crying that persists beyond 3 months of age in infants without other signs of neurological damage may be a marker for cognitive deficits during childhood. Such infants need to be examined and followed up more intensively.

This work confirms the work of Professor Dieter Wolke in the UK and Professor Wolke thinks the crying is a symptom rather than a cause of the underyling problem.

In 2002, a team of UK researchers, led by Professor Dieter Wolke at Bristol University, found children who had cried excessively as babies, beyond three months, were 14 times more likely to develop attention deficit hyperactivity disorder (ADHD) and do worse at school as eight year olds.

Professor Wolke said: "This confirms what we found.

"Now there really is more certainty there is really something going on."

He believes the core of the problem is one of under-regulation.

"With ADHD you can't regulate your attention. You can't concentrate, for example. The same thing is happening with crying.

One of the NIH scientists say that parents of babies who do uncontrollable crying should tell their pediatricians.

Such persistent, uncontrollable crying "seems to be a very good indicator of potential risk," Dr. Malla Rao of the National Institutes of Health in Bethesda, Maryland, told Reuters Health.

As such, Rao said, parents should not simply "dismiss" their child's crying as being due to gastrointestinal problems such as heartburn or colic, but should notify their child's pediatrician.

But it is unlikely the pediatricians will be able to deliver any sort of treatment that will prevent the eventual cognitive deficits. However, researchers probably ought to deliver a wide range of tests to a group of persistently crying babies to see if any toxin or pathogen might be causing neurological damage. If that was the case then an effective treatment could probably be devised. But if the cause of the neurological deficits is genetic or some event that happened at an earlier point in development then all the pediatrician is going to be able to say to parents is to plan on eventually giving you kid Ritalin when ADHD becomes a problem.

In the longer run this sort of discovery points to why biotech therapies for altering brain development will become acceptable. Imagine politicians trying to explain to young mothers that gene therapy or cell therapy for their continuously crying babies would constitute too much of an unnatural intervention. Mom is going to be thinking the crying means her baby is in pain and the fact that it will grow up dumb and hyperactive. She's going to demand that her Congressman votes to allow treatments that will make her kid happier, smarter, and calmer.

By Randall Parker    2004 November 05 02:31 PM   Entry Permalink | Comments (5)
2004 November 04 Thursday
Initial Bullying In Late In Adolescence Causes Most Harm

Matthew Newman and colleagues at UT Austin found that bullying leaves more lasting effects if it is first encountered in late adolescence.

People who were bullied all revealed slightly higher levels of stress. But while those bullied earlier in life seemed to respond normally to provocation, people bullied for the first time late in puberty are more withdrawn and sensitive to violence.

There are also sex differences between those bullied for the first time during puberty, with females more likely to react aggressively when provoked and males are much more likely to turn to alcohol to escape bad situations.

The stage of neuroendocrine system development in late adolescence may predispose toward a more lasting change in response to stress.

Newman admits that the results may seem counterintuitive, as older children might be expected to cope better with being bullied. But he points out that previous studies in animals and humans have shown that the reaction to bullying becomes more pronounced as puberty progresses. He suggests that children who are bullied earlier in puberty may be better prepared to cope with the more stressful experience of later victimization and so suffer fewer consequences in adulthood.

What is this an argument for? Vaccination from a lifetime of avoidance of conflict by use of early puberty bullying. Yes, you heard me. Kids need to get bullied early and often so that their first experiences with bullying will not come in late puberty. They need to build up emotional defenses that can only come from early bullying.

This result is consistent with the idea that people who grow up in tough neighborhoods are tougher emotionally. But the comparison here is between people who are bullied early versus people who are first bulled in late adolescence. Neither article linked to above mentions reactions of a control group of adults who were never bullied. Surely such people exist. Some kids grow up in really rural areas with few peers to bully them and some grow up so big for their age that their peers are afraid to bully them. So do bully-free kids grow up to handle stress well? Or do they lash out or slink away when provoked?

There is also the genetic angle to consider. The New Zealand Longitudinal Dunedin Multidisciplinary Health and Development Study found that a variation in the gene monoamine oxidase-A (MAOA or MAO-A) strongly predisposes abused children to become violent and criminal. It is possible that early childhood abuse is such a different experience for children than bullying during adolescence that abuse a different response than early or late adolescent bullying. Children may move through a series of stages where violence has different effects on their longer term development.

That there are children who carry an MAO-A variant that predisposes to greater violence in response to abuse argues for a reduction in the total amount of abuse children receive. But it becomes possible to genetically test each child for genetic variations that impact how children response to various types of mistreatment and rough treatment we may even find that it is beneficial for some children to get some bullying done to them at some stages whereas other children may be at risk of a worse outcome regardless of when they are abused or bullied.

By Randall Parker    2004 November 04 02:50 PM   Entry Permalink | Comments (9)
2004 November 01 Monday
Brain Development Leads To More Rational Restraint On Behavior

Kids are out of control because their medial temporal lobes have little say in what they do.

SAN DIEGO, Oct. 27 – A person's ability to have voluntary control over behavior improves with age because with development, additional brain processes are used, according to scientists at the University of Pittsburgh School of Medicine.

The research, presented today at the Annual Meeting of the Society for Neuroscience, helps to resolve questions about how working memory – a function that allows people to perform tasks as diverse as making toast to solving complex math problems – develops and changes from childhood to adulthood.

"This study gives us a good picture of how our ability to have voluntary control over our behavior using working memory changes and improves with maturity," said Beatriz Luna, Ph.D., associate professor of psychiatry at the University of Pittsburgh School of Medicine.

"Anyone with kids or teenagers knows that they can make irrational decisions when they are under stress," said Dr. Luna. "That is not just because they are trying to be difficult – kids simply are not yet able to access the brain regions that allow adults to react in a more controlled way. What this may mean is that adolescents may be able to act like adults under normal conditions, but under stress they may go back to a more instinctual, less thought-out response."

Note that stress increases memory recall but decreases problem-solving ability. Do middle-aged adults retain more problem-solving ability under stressful conditions than do young adults, adolescents, and children? Also, do criminals lose more problem-solving ability under stress than do non-criminal members of populations? Anyone know of there is any research literature on this question? It would be interesting to see whether the degree of decay of problem-solving ability under stressful conditions in adolescence correlates with future criminal behavior.

Working memory is where the brain stores information used to make immediate calculations, similar to the random access memory (RAM) in a computer. Like RAM, the information stored in working memory is dumped when it is no longer needed. Working memory allows the brain to take in information and create planned responses using abstract thought. Without it, human behavior would consist mostly of reflexive actions, and humans would not have been able to develop higher mental abilities.

In a group of 20 healthy 8- to 30-year-olds, Dr. Luna and her colleagues used a test called an oculomotor delayed response task to track memory-guided saccades (eye movements) while imaging their brains using functional magnetic resonance imaging (fMRI). Study participants briefly were shown a pinpoint of light and asked to remember where the light appeared. Ten seconds later, they were asked to look at the location where the light had been using just their memory. The 10-second time lapse was chosen because it would force the subjects to use their working memory – and not short- or long-term memory.

Results of the imaging study showed that pre-adolescent children relied most heavily on the prefrontal and parietal regions of the brain during the task; adolescents used those regions plus the anterior cingulate; and in adults, a third area of the brain, the medial temporal lobe, was brought in to support the functions of the other areas.

Adults did best with the saccade test probably because the medial temporal lobe helps refine encoding of information into working memory. In practical situations, introduction of the medial temporal lobe into the working memory process likely provides the kick needed to keep information around long enough and clearly enough for the brain to mull it over and make a rational, informed decision rather than an impulsive, reflexive action.

"Understanding working memory will inform us about how thinking occurs and how it is linked to other brain processes – and because working memory also is one of the major brain systems impaired in many psychiatric illnesses, understanding these links could inform the development of new treatments," said Dr. Luna.

This brings up an obvious question for those of us who expect medical treatments will be devised to change the speed and direction of brain development: Will it become possible to accelerate the growth of neurons and the development of connections in the brain to allow the medial temporal lobe to gain more influence on behavior at younger ages of child development? Will parents take their juvenile delinquents to get hormonal or gene therapies to enhance the connections the medial temporal lobe and the rest of the brain? Or will parole boards make the development such connections (verified by fMRI scans) as requirements for granting of parole to convicts?

This report is reason to be optimistic about one potential problem that may result from future rejuvenation therapies. A population made more youthful by rejuvenation may become more violent and criminal. While that is certainly going to happen to some extent this report suggests that when middle aged and old aged people can some day regain the use of fully rejuvenated and youthful bodies their rates of crime probably will not increase back up to the average level of criminal activity that their population cohorts engaged in when they were young. If the brain develops lasting neural wiring patterns into adulthood that give the rational brain a stronger ability to restrain impulses then my guess is that rejuvenation therapies will not reduce the strength of those neural connections.

By Randall Parker    2004 November 01 07:51 PM   Entry Permalink | Comments (2)
2004 October 27 Wednesday
Word Memory Shifts From Sound To Meaning As We Age

Somewhere between the age of 5 and the age of 11 human minds shift from associating words primarily by similarity of sounds to similarity of meaning.

The study found evidence of an age-related, developmental shift in language, suggesting that younger children process words primarily on the basis of phonology, or sound, while older children and adults process words primarily on the basis of semantics, or meaning. The findings are presented in the article "False Memories in Children: Evidence for a Shift from Phonological to Semantic Associations," by Steve Dewhurst and Claire Robinson of Lancaster University, United Kingdom. The article will be published in the November issue of Psychological Science, a journal of the American Psychological Society.


To test whether children would make similiar memory errors based on sound rather than semantics, the researchers used a version of this earlier experiment. They developed a list of words in which each word had at least one possible rhyme, then presented the list to children aged five, eight, or 11, who were asked to recall the words after hearing them. The results suggested a developmental correlation between age and language processes: The 11-year-olds performed in the same way as adults and falsely recalled words that were semantically related to the lists; the 8-year-olds were equally likely to falsely recall rhymes and semantic associates; and the 5-year-olds falsely recalled words that rhymed with those presented in the lists.

I think adults tend to forget and underestimate the intellectual difficulty of being a child because adults do not realize just how much contextual information they have built up and rely upon. For a child so much more of daily experience is novel and has no framework through which it can be sorted and organized.

For another demonstration of how minds develop better ways of classifying information as they age see my recent post Ferret Visual Cortex 80% Active Even In The Dark.

By Randall Parker    2004 October 27 04:11 PM   Entry Permalink | Comments (3)
2004 October 10 Sunday
Ferret Visual Cortex 80% Active Even In The Dark

While a popular myth holds that only about 10% of the neurons in our brains actually do anything Michael Weliky, associate professor of brain and cognitive sciences at the University of Rochester, investigated ferrets and found that young ferret brains may be less able to organize and make sense of visual stimuli, that young ferret brains are less busy in the dark than adult ferret brains, and that even in the dark 80% of adult ferret brain visual cortexes are still busy.

The test was then to see if there was any relationship between the statistical motion of the movie and the way visual neurons in the ferrets fired. Each visual neuron is keyed to respond to certain visual elements, such as a vertical line, that appears in a specific area of the ferret’s vision. A great number of these cells combine to process an image of many lines, colors, etc. By watching the patterns of how these cells fired while watching The Matrix, Weliky could describe the pattern statistically, and match those statistics of how the ferret responded to the film with the statistics of the actual visual aspects of the film.

Weliky found two surprises. First, while the neurons of adult ferrets statistically seemed to respond similarly to the statistics of the film itself, younger ferrets had almost no relationship. This suggests that though the young ferrets are taking in and processing visual stimuli, they’re not processing the stimuli in a way that reflects reality.

“You might think of this as a sort of dyslexia,” explains Weliky. “It may be that in very young brains, the processing takes place in a way that’s not necessarily disordered, but not analogous to how we understand reality to be. It’s thought that dyslexia works somewhat like this—that some parts of the brain process written words in an unusual way and seem to make beginnings of words appear at their ends and vice versa. Infant brains may see the entire world the same way, as a mass of disparate scenes and sounds.” Weliky is quick to point out that whatever way infant brains may interpret the world, just because they’re different from an adult pattern of perception does not mean the infants have the wrong perception. After all, an adult interpreted the visual aspects of the film with our adult brains, so it shouldn’t be such a surprise that other adult brains simply interpret the visual aspects the same way. If an infant drew up the statistics, it might very well match the neural patterns of other infants.

The second, and more surprising, result of the study came directly from the fact that Weliky’s research is one of the first to test these visual neurons while the subject is awake and watching something. In the past, researchers would perhaps shine a light at an unconscious ferret and note which areas of the brain responded, but while that method narrowed the focus to how a single cell responds, it eliminated the chance to understand how the neural network of a conscious animal would respond. Accepting all the neural traffic of a conscious brain as part of the equation let Weliky get a better idea of the actual processing going on. As it turned out, one of his control tests yielded insight into neural activity no one expected.

When the ferrets were in a darkened room, Weliky expected their visual neurons to lack any kind of activity that correlated with visual reality. Neurologists have long known that there is substantial activity in the brain, even in darkness, but the pattern of that activity had never been investigated. Weliky discovered that while young ferrets displayed almost no patterns that correlated with visual reality, the adult ferrets’ brains were humming along, producing the patterns even though there was nothing to see. When watching the film, the adult ferrets’ neurons increased their patterned activity by about 20 percent.

“This means that in adults, there is a tremendous amount of real-world processing going on—80 percent—when there is nothing to process,” says Weliky. “We think that if you’ve got your eyes closed, your visual processing is pretty much at zero, and that when you open them, you’re running at 100 percent. This suggests that with your eyes closed, your visual processing is already running at 80 percent, and that opening your eyes only adds the last 20 percent. The big question here is what is the brain doing when it’s idling, because it’s obviously doing something important.”

Since the young ferrets do not display similar patterns, the “idling” isn’t necessary for life or consciousness, but since it’s present in the adults even without stimulus, Weliky suggests it may be in a sense what gives the ferret its understanding of reality. The eye takes in an image and the brain processes the image, but 80 percent of the activity may be a representation of the world replicated inside the ferret’s brain.

There's an obvious math error in how this press release is written. If the brain is operating at 80% of capacity in the dark and then increases to 100% capacity then from the reference point of the brain's activity level in the dark the amount of increase going into a richer visual environment is actually 25%. But that is just a quibble.

A more basic problem is with the 100% figure for what is implied to be some sort of maximum activity level. Is that supposed to be the absolute maximum level of activity of a ferret brain's visual cortext? Isn't it possible that there are conditions under which a ferret visual cortex might become twice as active as the highest level of activity that this researcher ever measured? There has to be some absolute maximum level of activity because there is a limit to how much oxygen the bloodstream can deliver to neurons. Also, some neurons are going to be less active because the suppression of some neurons combines with the excitation of other neurons to form a representation of any one image.

All of these results are from ferrets and it is possible that human brains do not exhibit similar behavior. But my guess is that while the absolute percentages may differ from the numbers reported above human brains probably do have similar differences between babies and adults. The ability of adult brain visual cortexes to stay so active in the dark likely is the result of the development of a fairly complex model of the visual world. That model is always running and mulling over older images even when no new images are being presented to it.

What this suggests about babies and children is especially interesting. They can't make as much sense of the world. They do not know as many logical relationships between objects in an image field and therefore can't create as many higher level meanings from what they are seeing. So the visual world must seem far more random and unpredictable to them. They may not even have as great an ability to track temporal order of changes in elements in a visual field.

By Randall Parker    2004 October 10 01:07 PM   Entry Permalink | Comments (2)
2004 August 10 Tuesday
Premature Birth Produces More Lasting Brain Effects In Boys

Permanently smaller brain sizes in premature babies are an especially serious problem with premature boys.

STANFORD, Calif. – Kids on a playground can be hard to tell apart. But those who were born significantly preterm may be struggling with a hidden handicap that sets them apart from their peers: specific areas of the brain that are smaller than normal, even years later.

A collaborative study between the Stanford, Yale and Brown medical schools compared the brain volumes of two types of 8 year olds: those born prematurely and those born full-term. The researchers found significant, lingering reductions in the areas of the cerebral cortex responsible for reading, language, emotion and behavior. Even more surprising, the researchers discovered that the brains of preterm boys were more severely affected than were girls.

Boys born preterm do more poorly in school, have a harder time speaking, and are socially less able.

Doctors have known that preterm newborn boys fare more poorly than girls, but it’s not been clear why. The differences persist even after the early medical hurdles have been cleared: preterm boys struggle more than preterm girls with speech and language and have a harder time in academic and social situations as they grow older. Although it stands to reason that newborns making an unreasonably early appearance have smaller brain volumes than full-term babies, it wasn’t known that boys’ brains are more severely affected or that the disparity persists for so long.

By the description here among those born premature both males and females suffer from lower brain grey matter area. But only premature boys suffer from reduced white matter.

Reiss and Stanford co-investigator Shelli Kesler, PhD, collaborated with Laura Ment, MD, Betty Vohr, MD, and colleagues at Yale and Brown to compare brain-imaging data of 65 preterm children to 31 healthy, full-term children. Preterm babies were born at around 28 weeks of gestation and weighed about 2 pounds at birth. The study is published in the August issue of the Journal of Pediatrics.

“In the preterm group as a whole, we found the volumes of both grey matter and white matter were reduced,” said Reiss. “When we divided the preterm group by gender we found, bingo, the females had normal or preserved white matter volume, but the males’ volumes were reduced compared to their full-term peers.”

White matter is primarily made up of the axon connections and cells that facilitate communication between parts of the brain over distances, whereas grey matter consists of the cell bodies of the brain’s nerve cells, where signal processing and thinking happen. White matter lesions are responsible for the symptoms of multiple sclerosis, which compromise both mobility and cognitive functions.

“The adverse effects of preterm birth, such as hypoxia, expose the premature brain to an environment it’s not yet supposed to be in,” said Reiss. “Researchers have hypothesized that white matter might be preferentially affected, but sex-based differences have never been clearly shown until now.” Reiss speculates that girls may gain a measure of protection either through genetics or hormones.

The reduction in brain gray matter size that results from premature birth is also quite important because of the role that gray matter plays in determining intelligence. See my previous post Brain Gray Matter Size Correlated To Intelligence. Since intelligence is inversely correlated with criminality the increase in the number and survival rate of premature births may be boosting the crime rate.

The ability to save babies in troubled pregnancies using sophisticated medical technology is coming at a cost that includes not just the large sums of money spent on initial medical care but also the survival of babies that will grow up to be less intelligent, less socially adept, and economically less successful. At least some of the taxpayers money spent on funding the medical care that saves premature babies seems misplaced. The same number of dollars spent on isolating pregnant women who are cigarette smokers abusing drugs, and consuming alcohol would reduce the number of premature births and reduce the number of babies who will grow up with permanent mental and physical disabilities.

Premature births are now 12 percent of all births in the United States and cost $58,000 on average each as compared to $4,300 on average for normal births.

The five-year, $75 million awareness campaign was launched because premature births have risen 27 percent since 1981, resulting in tremendous cost to families, the medical system and society.

"Many of these babies come into the world with serious health problems. Those who survive may suffer lifelong consequences, from cerebral palsy and mental retardation to blindness," said Dr. Jennifer House, president of the March of Dimes.

Another factor contributing to the rising number of babies suffering from improperly developed brains is In Vitro Fertilization (IVF). Whether due to the age of the mother, other complications that prevented normal means of starting a pregnancy, or the IVF procedure itself, IVF pregnancies have at least double the rate of premature births.

There was limited evidence of a three times increased risk of having a very premature baby born prior to 32 weeks gestation.

In addition, there was just over a doubling of the risk of a "mildly" premature baby, born between 32 and 36 weeks.

What we need are technologies and practices that reduce the rate of premature births. So far most reproductive technologies appear to be making the problem worse. Technological advances are also making this problem worse by lowering the costs and increasing the availability of recreational drugs, alcohol, and cigarettes. My guess is that the reduction of exertion needed in daily life might also be contibuting to the problem. Technologies do not automatically make the human condition better. We need to develop technologies that adapt us better to those technologies that have caused many humans to behave in ways that are maladaptive and destructive.

By Randall Parker    2004 August 10 02:10 PM   Entry Permalink | Comments (55)
2004 June 28 Monday
Television Watching Lowers Melatonin, Hastens Puberty

"But Mom, I have to stay up late watching TV so I can grow up."

Scientists at the University of Florence in Italy found that when youngsters were deprived of their TV sets, computers and video games, their melatonin production increased by an average 30 per cent.

“Girls are reaching puberty much earlier than in the 1950s. One reason is due to their average increase in weight; but another may be due to reduced levels of melatonin,” suggests Roberto Salti, who led the study. “Animal studies have shown that low melatonin levels have an important role in promoting an early onset of puberty.”

Don't be too surprised if boys embarrassed by a lack of pubic hairs and girls wanting to grow breasts start watching more TV.

Turn off the TV to prevent teen pregnancy.

Alessandra Graziottin, director of the Centre for Gynaecology and Medical Sexology in Milan and a former president of the International Society for the Study of Women's Sexual Health, said the results were "very interesting and plausible".

She told the newspaper La Repubblica: "Studies in the US have shown that the greater the exposure to television the greater the number of early sexual experiences, including teen pregnancies."

I've previously argued for the delay of puberty in order to help kids be less distracted by sexual desires and more capable of learning. But the question hanging over this proposal is whether the delay of puberty will also delay brain changes that increase cognitive ability. We literally become smarter in our teen years and in recognition of this fact IQ tests are routinely normalized for age. We need psychometric research that tracks IQ changes as a function of the onset of puberty.

To get a sense of just how much the brain changes during adolesence see my post Adolescence Is Tough On The Brain.

By Randall Parker    2004 June 28 02:31 PM   Entry Permalink | Comments (4)
2004 May 17 Monday
Longitudinal Brain Scan Study Shows How Brain Matures

The brain develops in childhood and adolescence from back to front with the higher order brain centers developing last.

The brain's center of reasoning and problem solving is among the last to mature, a new study graphically reveals. The decade-long magnetic resonance imaging (MRI) study of normal brain development, from ages 4 to 21, by researchers at NIH's National Institute of Mental Health (NIMH) and University of California Los Angeles (UCLA) shows that such "higher-order" brain centers, such as the prefrontal cortex, don't fully develop until young adulthood.

A time-lapse 3-D movie that compresses 15 years of human brain maturation, ages 5 to 20, into seconds shows gray matter - the working tissue of the brain's cortex - diminishing in a back-to-front wave, likely reflecting the pruning of unused neuronal connections during the teen years. Cortex areas can be seen maturing at ages in which relevant cognitive and functional developmental milestones occur. The sequence of maturation also roughly parallels the evolution of the mammalian brain, suggest Drs. Nitin Gogtay, Judith Rapoport, NIMH, and Paul Thompson, Arthur Toga, UCLA, and colleagues, whose study is published online during the week of May 17, 2004 in The Proceedings of the National Academy of Sciences.

"To interpret brain changes we were seeing in neurodevelopmental disorders like schizophrenia, we needed a better picture of how the brain normally develops," explained Rapoport.

The researchers scanned the same 13 healthy children and teens every two years as they grew up, for 10 years. After co-registering the scans with each other, using an intricate set brain anatomical landmarks, they visualized the ebb and flow of gray matter - neurons and their branch-like extensions - in maps that, together, form the movie showing brain maturation from ages 5 to 20.

It was long believed that a spurt of overproduction of gray matter during the first 18 months of life was followed by a steady decline as unused circuitry is discarded. Then, in the late l990s, NIMH's Dr. Jay Giedd, a co-author of the current study, and colleagues, discovered a second wave of overproduction of gray matter just prior to puberty, followed by a second bout of "use-it-or-lose-it" pruning during the teen years.

The new study found that the first areas to mature (e.g., extreme front and back of the brain) are those with the most basic functions, such as processing the senses and movement. Areas involved in spatial orientation and language (parietal lobes) follow. Areas with more advanced functions -- integrating information from the senses, reasoning and other "executive" functions (prefrontal cortex) - mature last.

In a related study published a few years ago, Rapoport and colleagues discovered an exaggerated wave of gray matter loss in teens with early onset schizophrenia. These teens, who became psychotic prior to puberty, lost four times the normal amount of gray matter in their frontal lobes, suggesting that childhood onset schizophrenia "may be an exaggeration of a normal maturation process, perhaps related to excessive synaptic pruning," note the researchers. By contrast, children with autism show an abnormal back-to-front wave of gray matter increases, rather than decreases, suggesting "a specific faulty step in early development."

Also participating in the new study were: Leslie Lusk, Cathy Vaituzis, Tom Nugent, David Herman, Drs. Deanna Greenstein, Liv Clasen, NIMH; Kiralee Hayashi, UCLA.

This next article reviews a number of recent studies on brain development and includes quotes from scientists arguing over whether the brain scan studies and other advances in neurobiology are evidence for reducing the legal responsibility of adolescents for criminal actions.

The ambiguities of science don't mix with social and political causes, contends neuroscientist Bradley S. Peterson of the Columbia College of Physicians and Surgeons in New York City. For instance, it's impossible to say at what age teenagers become biologically mature because the brain continues to develop in crucial ways well into adulthood, he argues.

A team led by Sowell and Peterson used an MRI scanner to probe the volume of white and gray matter throughout the brains of 176 healthy volunteers, ages 7 to 87. The researchers reported in the March 2003 Nature Neuroscience that myelin formation—measured by the total volume of white matter in the entire brain—doesn't reach its peak until around age 45.

Although gray matter volume generally declines beginning around age 7, it steadily increases until age 30 in a temporal-lobe region associated with language comprehension.

That previous article opens up with arguments by David Fassler and Ruben Gur against the application of the death penalty to adolescents. Fassler and Gur believe the brains of adolescents are not yet fully enough formed to allow them to understand the intentions of others or to control themselves. Surely there is lots of evidence for on-going changes in the brain in adolescence and beyond. Some of the results are a bit surprising. For instance, while language processing starts out on one side of the brain language processing becomes more evenly distributed across both sides of the brain in one's mid-20s.

It has been known for some time that children have sharp growth spurts in brain connections among regions specialized for language and spatial relationships between ages 6 and 12. That language capacity tends to reside mostly in a person's nondominant side - the left hemisphere of the brain in right-handers, for instance. But a recent imaging study by researchers at the University of Cincinnati Medical Center found that this distinction ends in the mid-20s when the brain shifts to use both sides in language processing.

One particularly important (yet still preliminary) finding about adolescents by Deborah Yurgelun-Todd and colleagues at Harvard and McLean Hospital is that adolescents tend to misinterpret fearful expressions on faces as anger or other emotions.

What does your work tell you about young teenagers?

One of the implications of this work is that the brain is responding differently to the outside world in teenagers compared to adults. And in particular, with emotional information, the teenager's brain may be responding with more of a gut reaction than an executive or more thinking kind of response. And if that's the case, then one of the things that you expect is that you'll have more of an impulsive behavioral response, instead of a necessarily thoughtful or measured kind of response.

Does this research go part of the way to explaining the miscues between adult and teenagers?

Yes, I do think this research goes to helping understand differences between adults and teenagers in terms of communications. And I think that it does for two reasons. One, we saw that adults can actually look at fearful faces and perceive them as fearful faces, and they label them as such, whereas teenagers ... don't label them the same way. So it means that they're reading external visual cues [differently], or they're looking at affect differently.

The second aspect of the findings are that the frontal region, or this executive region, is activating differentially in the teenagers compared to adults. And I think that has important implications in terms of modulating their own responses, or trying to inhibit their own gut responses.

But even if all the evidence does point to problems with adolescent brains that is not necessarily an argument for less severe punishment for adolescents. One reason for that is the lower levels of punishment can be ruthlessly exploited by adolescents aware of the fact that they face less severe consequences for their actions. Also, if adolescents really are more prone to violent behavior then perhaps more severe punishment is needed to deter them than is needed deter adults.

My more fundamental objection to the argument for reduced legal liability is that it can not be enacted unilaterally without other compensatory changes. A free society is built on the assumption that its members are competent moral agents. While this is obviously not always true and scientific advances are likely going to chip away at that assumption even more in the future it really is a necessary assumption for a free society. People are given a great deal of latitude on what they can do and what legal protections they have because most are considered to be morally competent.

A reduction in assumed moral competence would need to be accompanied with a reduction in latitude of actions and autonomy which is allowed. For example, of kids can't be punished as severely as adults for, say, killing someone on the streets at night then it doesn't make sense to allow kids to be out on the streets at night in the first place. Or once it becomes possible to measure individual tendencies to violence perhaps a biotechnologically more advanced response might be to require teens to be tested for indicators of violent tendencies. Then those who are most at risk of lashing out could be given the choice of either drugs to reduce violent urges or exile to a remote special community designed to handle dangerous adolescents until their brains develop enough to allow their prefrontal cortexes to reign in their more primitive urges.

While some may quibble with these specific suggestions the larger point here is that regardless of the particular methods chosen to respond society needs to be protected from brains that are not operating as fully responsible moral agents.

Also see my previous post Adolescence Is Tough On The Brain.

By Randall Parker    2004 May 17 09:48 PM   Entry Permalink | Comments (6)
2004 February 25 Wednesday
Adolescent Brains Are Less Motivated

The proverbial listless and directionless adolescents are wired up to be less motivated than adults.

In the MRI study, James Bjork, Ph.D., and others in the laboratory of Daniel Hommer, M.D., scanned the brains of twelve adolescents aged 12 to 17 years and twelve young adults aged 22 to 28 years. While being scanned, the subjects participated in a game-like scenario risking monetary gain or loss. The participants responded to targets on a screen by pressing a button to win or avoid losing 20 cents, $1, or $5.

For both age groups, the researchers found that the anticipation of potential gain activated portions of the ventral striatum, right insula, dorsal thalamus, and dorsal midbrain, with the magnitude of ventral striatum activation sensitive to gain amount. In adolescents, however, the researchers found lower activation of the right ventral striatum centered in the nucleus accumbens, a region at the base of the brain shown by earlier research (see Alcohol Researchers Localize Brain Region That Anticipates Reward August 3, 2001 at News Releases-http://www.niaaa.nih.gov) to be crucial for motivating behavior toward the prospect of rewards.

"Our observations help to resolve a longstanding debate among researchers about whether adolescents experience enhanced reward from risky behaviors--or seek out alcohol and other stimuli because they require enhanced stimulation. They also may help to explain why so many young people have difficulty achieving long-term goals," according to James Bjork, Ph.D., first author on the study.

When the researchers examined brain activity following gain outcomes, they saw that in both adolescents and young adults monetary gain similarly activated a region of the mesial frontal cortex. "These results suggest that adolescents selectively show reduced recruitment of motivational but not consummatory components of reward-directed behavior," state the authors.

In a nutshell: adolescents want stuff but they are too lazy to work to get as much as they want. Worse yet, they have few skills with which to work to get what they want. No wonder they frustrated, depressed, and angry.

The mentioned earlier research is here: Alcohol Researchers Localize Brain Region That Anticipates Reward

Researchers in the laboratory of Daniel Hommer, M.D., measured changes in blood oxygen level dependent contrast in a functional magnetic resonance (FMRI) scanner in order to track changes in brain activity that occurred while eight volunteers participated in a videogame task involving real money. In this monetary incentive delay (MID) task, participants saw cues that indicated that they might win or lose money, waited for a variable anticipatory delay period, then tried to either win or avoid losing money by pressing a button in response to a rapidly presented target. The researchers examined the response of the nucleus accumbens during anticipation of different amounts of potential rewards (i.e., gains of $0.20, $1.00, and $5.00) or punishments (i.e., losses of $0.20, $1.00, and $5.00). They found that nucleus accumbens activity increased as volunteers anticipated increasing monetary rewards but not punishments. Another nearby brain region, the medial caudate, showed increased activity not only during anticipation of increasing rewards but also during anticipation of increasing punishments.

Imagine a drug or gene therapy that stimulates the growth or activity of the nucleus accumbens. It might make adolescents and even adults more motivated. The educational and economic effects of such therapies could be enormous.

By contrast, stimulation of growth of the appropriate portion of the medial caudate might be more useful for treating criminals. If criminals could be made to have a greater fear of punishment they might become less likely to violate the law. I'm betting that most criminals will eventually be found by brain scan studies to have a lower fear of punishment than the population as a whole.

For more on young brains see my previous posts Adolescence Is Tough On The Brain and Adolescent Mice More Sensitive To Addictive Drugs and Early Nicotine Exposure Increases Nicotine Craving.

By Randall Parker    2004 February 25 11:06 AM   Entry Permalink | Comments (4)
2003 November 21 Friday
Steroid Use May Increase Aggressiveness Long Term

Anabolic steroid use may cause permanent changes in personality and behavior.

(11-20-03) BOSTON, Mass. – With the recent revelations about steroid use in Major League Baseball and the bust last week of several Oakland Raiders players for drug abuse, Northeastern University psychology professor Richard Melloni, who studies the link between steroid use and aggression, has recently found evidence that use of anabolic steroids may have long-term effects on players’ behavior and aggression levels well after they stop abusing these performance enhancing drugs.

With funding from the NIH (recently extended through 2008), Melloni and doctoral student Jill Grimes have been studying how steroids used during adolescence may permanently alter the brain's ability to produce serotonin. In their experiments, adolescent Syrian hamsters - given their similar brain circuitry to human adolescents – were administered doses of anabolic steroids and then measured for aggressiveness over certain periods of time.

The researchers initially hypothesized that steroid use during adolescence might permanently alter the brain's chemistry and a person's tendency toward aggression long after use has stopped. Their most recent findings, published this week in Hormones and Behavior, enabled them to confirm this hypothesis and conclude that there is indeed a lengthy price – namely long-term aggression – to pay for drug abuse even after the ingestion of steroids ceases. “We know testosterone or steroids affect the development of serotonin nerve cells, which, in turn, decreases serotonin availability in the brain,” Melloni says. “The serotonin neural system is still developing during adolescence and the use of anabolic steroids during this critical period appears to have immediate and longer-term neural and behavioral consequences. What we know at this point is that aggressiveness doesn’t simply cease after the ingestion of steroids does.”

Based on this research, Melloni also believes that athletes who abuse steroids may also be inclined toward aggressive behavior long after their drug abuse – and musculature – have waned.

The press release doesn't detail their findings unfortunately. But the claims here are at least plausible. See my previous posts on reports about drugs and environmental influences causing changes to brain development: Drugs And Stress Have Variety Of Effects On Brain Development and Adolescence Is Tough On The Brain.

By Randall Parker    2003 November 21 01:20 PM   Entry Permalink | Comments (3)
2003 October 20 Monday
Fetal Brain Gene Expression Patterns Differ By Sex

Mouse fetus brain gene expression differs by the sex of the fetus.

Halfway into a mouse pregnancy, before the testes have even formed, the activity of 51 genes is different in males and females, says Eric Vilain of the University of California, Los Angeles. His team analysed 12,000 brain genes.

Note that other news accounts report 54 genes are involved.

These gene expression differences are found before genital hormone manufacture could possibly begin to play a role in influencing sexual development of the brain.

It rebuts 30 years of scientific dogma that the hormones, estrogen and testosterone, alone were responsible for differences between the male and female brain. So the researchers were surprised then they found 54 genes produced in different amounts in male and female brains prior to hormonal influence. Eighteen of the genes were produced at higher levels in the male brains and 34 were produced at higher levels in the female brains.

This opens up some interesting possibilities. If a large set of genes all express one way in females and in a different way in males then it may become possible to manipulate subsets of the genes involved in making male and female brains to create people who are in some ways female and in other ways male. Also, by pushing the expression of the genes more in one direction or the other it may eventually be possible to make even more masculine and more feminine minds.

I have a basic rule: the more we learn about the genetic basis of human nature the more we will be able to manipulate it. Abuses are inevitable. Also, the culture wars about abortion rights will seem like the little leagues as compared to the future battles about ethics when it becomes possible to change human nature by manipulating the development of the mind. Real physical wars may end up being fought over different visions of what is allowable to do in creating offspring.

This report also brings up the question of whether any of those who want to undergo a sex change operation experienced during fetal development genetic expression patterns that are more like those the opposite sex. Also, the same question can be asked about homosexuals. The difficulty of answering these questions is that getting neurons out of a brain to test would pose ethical and practical problems and it would take years to wait to see if the fetal stage gene expression patterns have gene expression patterns that are, at least in some respects, more like the opposite sex? My guess is that the homosexuals will turn out to have various mixes of male and female brain gene expression patterns.

Sexuality is looking more and more to be biologically based.

"Our findings may help answer an important question -- why do we feel male or female?" Dr. Eric Vilain, a genetics professor at the University of California, Los Angeles School of Medicine, said in a statement. "Sexual identity is rooted in every person's biology before birth and springs from a variation in our individual genome."

This is another nail in the coffin of the tabula rasa view of human nature.

This result may eventually be useful for more accurately identifying and treating those born with sexually ambiguous genitalia.

"If physicians could predict the gender of newborns with ambiguous genitalia at birth, we would make less mistakes in gender assignment," said Vilain.

This report follows and certainly builds on work by a team headed by Vilain reported a year ago that showed that the brain started getting sexual orientation before the SRY gene starts genital development. See the post Brain Gets Sex Orientation Before Genitals for more details.

Update: It would be interesting to compare liver gene expression patterns in homosexuals to heterosexuals to see if liver gene expression differs from male and female expression patterns in homosexuals.

In the November 1 issue of Genes & Development, Dr. Diane Robins and colleagues report on their discovery of two neighboring genes, Rsl1 and Rsl2, that repress male-specific liver gene expression in female mice. They found that female mice harboring mutations in Rsl genes aberrantly turn on male-specific liver genes, causing the female livers to adopt characteristically male patterns of gene expression.

If liver gene expression patterns were to turn out in some cases to be reliable proxies for brain gene expression patterns for genes that are sex-specific then that might make it easier to test for sex-specific gene expression patterns.

Update II: The UCLA press release contains more details on the Vilain study.

"We didn't expect to find genetic differences between the sexes' brains," Vilain said. "But we discovered that the male and female brains differed in many measurable ways, including anatomy and function."

In one intriguing example, the two hemispheres of the brain appeared more symmetrical in females than in males. According to Vilain, the symmetry may improve communication between both sides of the brain, leading to enhanced verbal expressiveness in females.

"This anatomical difference may explain why women can sometimes articulate their feelings more easily than men," he said.

Overall, the UCLA team's findings counter the theory that only hormones are responsible for organizing the brain.

"Our research implies that genes account for some of the differences between male and female brains," Vilain said. "We believe that one's genes, hormones and environment exert a combined influence on sexual brain development."

The scientists will pursue further studies to distinguish specific roles in the brain's sexual maturation for each of the 54 different genes they identified. What their research reveals may provide insight into how the brain determines gender identity.

Men and women really do think differently.

By Randall Parker    2003 October 20 08:22 PM   Entry Permalink | Comments (5)
2003 July 21 Monday
Excessive Speed Of Brain Growth May Cause Autism

Smaller than average baby brains that grow very rapidly in the first year of life are seen as key to the development of autism.

Small head circumference at birth, followed by a sudden and excessive increase in head circumference during the first year of life, has been linked to development of autism by researchers at the University of California, San Diego (UCSD) School of Medicine and Children’s Hospital and Health Center, San Diego. Autism spectrum disorder occurs in one out of every 160 children and is among the more common and serious of neurological disorders of early childhood.


It was found that the head size of the autistic children at birth was, on average, in the 25th percentile, meaning that the circumference measurement for these children was smaller than 75 percent of other newborns. During the first year of life, however, these same children experienced sudden, rapid and excessive brain growth, that put them in the 85th percentile at about 12- to 14-months of age. From then on, the brain growth slowed.

“This burst of overgrowth takes place in a brief period of time, between about two months and six to 14 months of age,” Courchesne said. “So, we know it cannot be caused by events that occur later, such as vaccinations for mumps, measles and rubella or exposure to toxins during childhood.”

Although no one has yet determined the biological cause of autism, the new findings “give us information about the timing of abnormal brain development,” said study co-author Ruth Carper, Ph.D., a post-doctoral researcher in the UCSD Department of Neurosciences and a research associate at Children’s. “This provides a timeframe for further research, to determine the exact brain abnormalities and the biological mechanisms which produce them.”

Is the rapid rate of brain growth a consequence of a brain growth regulatory system's sensing and responding to the fact that the brain is smaller than it ought to be?

This result will enable the detection of risk for autism at a much younger age. But what is needed is the ability to intervene in the regulatory systems that control brain growth. If research on autism leads to knowledge about how to control brain growth it may become possible to also use that knowledge to boost intelligence by intervening in baby brain development.

By Randall Parker    2003 July 21 11:22 PM   Entry Permalink | Comments (2)
2003 June 20 Friday
Shyness In Babies Detectable By MRI Brain Amygdala Scans

Functional Magnetic Resonance (fMRI) brain scans done on adults show patterns in adult brain activity that correlate with shyness of those same people as toddlers.

A key area in the brains of people who displayed an inhibited temperament as toddlers shows a greater response to new faces than does the same brain area in adults who were uninhibited early in life, according to a study by researchers from Massachusetts General Hospital (MGH). The imaging studies of the amygdala – a part of the brain that responds to events requiring extra vigilance – appear in the June 20 issue of Science.

"Our findings both support the theory that differences in temperament are related to differences in amygdala function, something earlier technology could not prove, and show that the footprint of temperamental differences observed when people are younger persist and can be measured when they get older," says Carl Schwartz, MD, director of the developmental psychopathology lab in the MGH Psychiatric Neuroscience Program, the paper's first author. "In a way, this research is the neuroscientist's version of the 'Seven-Up' movies," he adds, referring to a well-known series of British documentaries that have revisited a group of people every seven years for more than 40 years.

In psychological terms, temperament refers to a stable emotional and behavioral profile that is observed in infancy and partially controlled by genetic factors. One of the most carefully studied temperamental measures relates to a child's typical response to unfamiliar people, objects and situations. It usually is described with terms such as shyness versus sociability, caution versus boldness, or withdrawal versus approach. The two extremes of this measurement define types of children called inhibited and uninhibited by Jerome Kagan, PhD, professor of Psychology at Harvard University, a co-author of the current study.

The study participants were 22 young adults who, as children, had participated in Kagan's earlier research. Thirteen of the participants had been determined to be inhibited as infants, and nine were categorized as uninhibited. In the first phase of the current study, functional MR images (fMRI) were taken while participants viewed a random series of six faces that were presented several times. In the test phase, participants viewed a larger number of faces, some of which were totally new and some that were repeated from the first phase. All of the faces that the participants viewed had expressions that were neutral and not characterized by any emotion.

While some increase in amygdala response to strange faces is normal, the inhibited participants showed a significantly greater response to the unfamiliar faces than did the uninhibited participants. Two of the inhibited participants previously had been diagnosed with the anxiety disorder social phobia, but even when their results were removed from analysis, the inhibited groups showed much greater amygdala response.

"It's been theorized that the behavioral differences that characterize inhibited and uninhibited children may relate to the amygdala's response to novelty, and our study supports that concept," says Schwartz, who is assistant professor of Psychiatry at Harvard Medical School. "This was a modest study that needs to be confirmed in a larger population, something we are hoping to receive the resources to carry out."

The researchers also note that the current findings could complicate the interpretation of psychiatric imaging studies. Schwartz notes, "There are many imaging studies that have compared people with anxiety disorders such as panic disorder and social phobia to normal controls and found increased amygdalar activity.

While the conventional interpretation of such studies is to regard these differences as markers of the illness, our results suggest that this brain activity may in fact be a marker for the continued influence of temperamental risk factors persisting from infancy."

"These findings may reflect a difference in vulnerability that can be compensated for or exacerbated by environment and experience," says Scott Rauch, MD, MGH director of psychiatric neuroimaging, another co-author of the Science paper.

Two year old babies already have distinct recognizeable differences in their reactions to new situations.

"Inhibited children in the second year of life don't like novelty, don't like unknown situations," Schwartz said in a telephone interview. "It is broader than shyness ... It is about being more vigilant about things that are new

The differences in the temperament of babies are easily observable.

"A grad student made a little R2D2 robot," Schwartz said. "The uninhibited toddlers would walk up and poke the robot in the eye and say 'duh.' The inhibited child would freeze or even run to his mother."

There are long term behavior differences between inhibited and uninhibited children.

These temperaments are widely thought to be inborn, and each carries risks. Uninhibited children can become aggressive and antisocial in adolescence and adulthood, while inhibited children are more prone to anxiety disorders.

Anxiety is more common among inhibited people.

The findings may help to start sorting out the nature-versus-nurture debate. About one-third of "inhibited" children end up with social anxiety disorder, versus only 9 percent of "uninhibited" ones.

If these differences in temperament which are evident from such an early age are at least partially genetically based then eventually it will become possible to do genetic engineering to create babies with different temperaments.

Early amygdala differences persist for decades.

Dr Schwartz said: "It's been theorised that the behavioural differences that characterise inhibited and uninhibited children may relate to the amygdala's response to novelty, and our study supports that concept. Now we're suggesting that the same link continues through life. We found that individual differences in temperament are associated with persistent differences in the response of the amygdala after more than 20 years of development and life experience."

By Randall Parker    2003 June 20 11:31 AM   Entry Permalink | Comments (1)
2002 November 13 Wednesday
Tomboys The Result Of Maternal Testosterone

Higher maternal testosterone levels in pregnant women correlate with tomboy behavior in young femal children:

"Because hormones influence basic processes of brain development, they also exert permanent influences on behavior," says lead author Melissa Hines, Ph.D., of City University in London "In both rats and rhesus monkeys, genetic female animals treated with testosterone during critical periods of prenatal or early postnatal life show increased levels of … male-typical play behavior as juveniles."

Hines and her co-authors note that girls with congenital adrenal hyperplasia (CAH), a genetic disorder involving prenatal exposure to high levels of male hormones, tend to prefer masculine-typical toys and activities.

The study results appear in the November-December issue of Child Development.

Participants were part of the Avon Longitudinal Study of Parents and Children, a long-term study of biological, environmental and social factors associated with pregnancy outcomes and child health. A total of 13,998 pregnant women -- who represented 90 percent of all pregnancies occurring in the Avon, England, area during an 18-month period in the early 1990s -- enrolled in the study. Data from 679 offspring of the 14,138 children born during the study were analyzed.

The researchers obtained blood samples from the pregnant women during routine prenatal medical care; 55 percent of the women had blood taken between weeks 8 and 24 of the pregnancy; a quarter of the women had the samples taken between weeks 5 and 7, and the remainder after week 25. The samples were analyzed for levels of testosterone and a hormone that limits the ability of testosterone to act, called sex hormone binding globulin.

Once each child reached age 3 1/2, a primary caregiver completed the Pre-School Activities Inventory (PSAI), which assesses the child's engagement in various sex-typed behaviors, such as play with certain toys, games and activities. Higher scores indicate more masculine-typical behavior. The questionnaire was completed again when the child was 3 1/2.

The authors found a link between testosterone level in mothers and girls' scores on the PSAI, with high testosterone levels related to high "masculine" scores. No relationship was found between testosterone levels and boys' gender-role behavior, however.

In case it seems odd that I post alot on research about neurobiology and behavior on a blog dedicated to the future I'd like to explain why I do this. These studies demonstrate jut how much of human nature is determined by genes and by hormones and other biochemical factors that regulate genetic expression. In the future we are going to be able to make choices about the genetic sequences of genes for our offspring and we therefore will be able to change the mental aspects of human nature. It is important to appreciate just how many ways biological variations can cause variations human minds and human behavior because all of those variations and many more will be manipulated intentionally. When we acquire the ability to control gene that determine personality characteristics in offspring this it will simultaneously provide a great benefit and pose a great threat. It is important that we start thinking about this topic now.

By Randall Parker    2002 November 13 02:21 PM   Entry Permalink | Comments (3)
2002 November 12 Tuesday
Adolescence Is Tough On The Brain

First off, kids enterting puberty experience a big drop in their ability to read the emotions of others. So suddenly the likelihood for misunderstandings shoots way up:

Robert McGivern and his team of neuroscientists at San Diego State University found that as children enter puberty, their ability to quickly recognise other people's emotions nosedives. What's more, this ability does not return to normal until they are around 18 years old. McGivern reckons this goes some way towards explaining why teenagers tend to find life so unfair, because they cannot read social situations as efficiently as others.

Previous studies have shown that puberty is marked by sudden increases in the connectivity of nerves in parts of the brain. In particular, there is a lot of nerve activity in the prefrontal cortex. "This plays an important role in the assessment of social relationships, as well as planning and control of our social behaviour," says McGivern.

He and his team devised a study specifically to see whether the prefrontal cortex's ability to function altered with age. Nearly 300 people aged between 10 and 22 were shown images containing faces or words, or a combination of the two. The researchers asked them to describe the emotion expressed, such as angry, happy, sad or neutral.

The team found the speed at which people could identify emotions dropped by up to 20 per cent at the age of 11. Reaction time gradually improved for each subsequent year, but only returned to normal at 18 (Brain and Cognition, vol 50, p 173).

During adolescence, social interactions become the dominant influence on our behaviour, says McGivern. But at just the time teenagers are being exposed to a greater variety of social situations, their brains are going through a temporary "remodelling", he says. As a result, they can find emotional situations more confusing, leading to the petulant, huffy behaviour adolescents are notorious for.

This study may not have used subjects with an early enough starting age to detect the initial decline in ability detected in the previous study:

Another series of MRI studies is shedding light on how teens may process emotions differently than adults. Using functional MRI (fMRI), a team led by Dr. Deborah Yurgelun-Todd at Harvard's McLean Hospital scanned subjects' brain activity while they identified emotions on pictures of faces displayed on a computer screen.5 Young teens, who characteristically perform poorly on the task, activated the amygdala, a brain center that mediates fear and other "gut" reactions, more than the frontal lobe. As teens grow older, their brain activity during this task tends to shift to the frontal lobe, leading to more reasoned perceptions and improved performance. Similarly, the researchers saw a shift in activation from the temporal lobe to the frontal lobe during a language skills task, as teens got older. These functional changes paralleled structural changes in temporal lobe white matter.

During a time period when teens are already having a hard enough time sorting thru their own emotions they become far more sensitive to emotion-altering recreational drugs:

Researchers at Jefferson Medical College have evidence in animals that the young, adolescent brain may be more sensitive to addictive drugs such as cocaine and amphetamines than either the adult or newborn. The work may help someday lead to a better understanding of how the adolescent human brain adapts to such drugs, and provide clues into changes in the brain that occur during drug addiction.

Scientists led by Michelle Ehrlich, M.D., professor of neurology at Jefferson Medical College of Thomas Jefferson University in Philadelphia and a member of the Farber Institute for Neurosciences at Jefferson, and Ellen Unterwald, Ph.D., associate professor of pharmacology at the Temple University School of Medicine in Philadelphia, found a greater increase in a certain protein in the part of the adolescent mouse brain called the striatum following chronic exposure to drugs such as amphetamine or cocaine than they did in either very young mice or adults.

Such psychostimulant drugs affect the brain's striatum in different ways, potentially affecting both movement and locomotion, or the "reward" system. This "molecular adaptation," says Dr. Ehrlich, could be significant. "An increase in this protein may be important because it could also affect other molecules that could lead to long-lasting changes in the brain in response to psychostimulant drugs." The protein, called Delta FosB, is a transcription factor and plays a role in regulating gene expression. Earlier research by other scientists had shown increased amounts of Delta FosB in adult brains following chronic exposure to psychostimulants.

The team, which includes scientists at the Nathan Kline Institute in Orangeburg, New York, reports its findings November 1 in the Journal of Neuroscience.

Teens are at risk of developing life long harmful habits and their brains change in a way to puts them at greater risk of developing addiction to the demon weed:

When they did, researchers at Duke University found that adolescent brains respond more intensely to nicotine. The scientists injected rats with nicotine every day for more than two weeks, a dose comparable to what a typical smoker receives. In all of the rats the number of chemical receptors dedicated to nicotine increased -- a sign of addiction. But in adolescents, the number of nicotine receptors increased twice as much compared to adults.

"What we found is that the adolescent brain gets a lot more bang for the buck," says Theodore Slotkin, one of the scientists who performed the research.

A follow-up study published in the October issue of Brain Research showed that adolescent nicotine exposure caused permanent behavioral problems as well, especially for females. Even after two weeks with no nicotine, female rats were less interested in moving around and raising their young than counterparts who had never been exposed.

That may be because nicotine retards cell division in the hippocampus, a brain region that continues growing into adulthood in females, but not males.

The larger society is forcing teenagers to wake up earlier than their teen biological clocks are telling them to:

When teenagers insist that they are not tired at 9 or 10 p.m., they are very likely telling the truth. For reasons that are not fully understood, Dr. Carskadon said, their body clocks shift, so that their natural tendency is to stay up later at night and wake up later in the morning than when they were younger. But that inner clock often clashes with the outer world: early starting times in high school and demanding schedules of sports, clubs, music lessons, homework and part-time jobs.

There are consequences. For one thing, lack of sleep can interfere with learning: tired students have a hard time paying attention, and even if they do somehow manage to focus, they may forget what they were taught because memory formation takes place partly during sleep.

In "Adolescent Sleep Patterns," a book published in August and edited by Dr. Carskadon, she wrote, "The students may be in school, but their brains are at home on their pillows."

What's worse, the types of brain activities engaged in during adolescence probably have a significant impact on what cognitive abilities people will have the rest of their lives:

Even though it may seem that having a lot of synapses is a particularly good thing, the brain actually consolidates learning by pruning away synapses and wrapping white matter (myelin) around other connections to stabilize and strengthen them. The period of pruning, in which the brain actually loses gray matter, is as important for brain development as is the period of growth. For instance, even though the brain of a teenager between 13 and 18 is maturing, they are losing 1 percent of their gray matter every year.

Giedd hypothesizes that the growth in gray matter followed by the pruning of connections is a particularly important stage of brain development in which what teens do or do not do can affect them for the rest of their lives. He calls this the "use it or lose it principle," and tells FRONTLINE, "If a teen is doing music or sports or academics, those are the cells and connections that will be hardwired. If they're lying on the couch or playing video games or MTV, those are the cells and connections that are going to survive."

On the bright side, the spurts in cell growth in various parts of the brain during adolescence open up the possibility of therapies to boost intelligence by developing hormonal and/or gene therapies that would make the burst of nerve growth more intense. Also, with better understanding it may become possible to structure the institutions that deal with adolescents to better accommodate the developmental stages of their brains. Obviously, just moving starting times forward for schools is a fairly easy accommodation.

Update: These results provide a sense of just how much the mind changes during adolescence:

Researchers at studied the post-mortem cerebral cortexes of six 12- to 17-year-olds and five 17- to 24-year-olds. All of the individuals had been of normal health and intelligence. They studied 43 different areas in each brain hemisphere, measuring for cortical thickness, neuronal density and pyramidal neuronal size. Corrections were made for gender differences in the size of the brain.

The average pyramidal soma size was 15.5 percent smaller in the older age group than in the younger one. This suggests that these nerve cells undergo “pruning” or “streamlining” of their processing during adolescence, said de Courten-Myers.

Other measures of the brain were slightly larger in the older age group, including cortical thickness (1.9 percent), neural density (1.8 percent), the number of neurons/standard cortical columns (3.8 percent), neuropil volume/standard cortical column (3.1 percent), and neuropil volume/neuron (1.3 percent).

Update II The part of the brain that inhibits risky behavior does not fully develop until age 25.

A National Institutes of Health study suggests that the region of the brain that inhibits risky behavior is not fully formed until age 25, a finding with implications for a host of policies, including the nation's driving laws.

"We'd thought the highest levels of physical and brain maturity were reached by age 18, maybe earlier -- so this threw us," said Jay Giedd, a pediatric psychiatrist leading the study, which released its first results in April. That makes adolescence "a dangerous time, when it should be the best."

So that is why teenagers are so reckless. Hardly comforting news. You can know this and they will still be reckless after all.

By Randall Parker    2002 November 12 12:20 PM   Entry Permalink | Comments (21)
2002 October 19 Saturday
Brain Gets Sex Orientation Before Genitals

The SRY gene is widely considered as the gene for determining sexual identity. See for instance this page about the role of the SRY gene in determining sexual identity. Also, see this page:

By its structure, the SRY gene is a 1,0 kb one exon gene located just centromeric to the pseudoautosomal region of Yp functioning as the dominant inducer of testis development. This gene comprises a single exon that encodes a 203- amino acid protein. The middle third of the protein represents the HMG (high-mobility group) domain specifically binging to a target nucleotide sequence 5’-AACAAAG-3’ characterising it as a transcription regualtor protein. Although its function is not entirely known, this gene is obviously the first initiator of male sexual differentiation 13, 19, 37, 42.

However, a UCLA team led by Eric Vilain has discovered differences in genetic expression that happen before the SRY gene becomes active during development. It is possible that male-female brain differences start developing before SRY starts changing genitals development:

"But in a study of mice, a team at the University of California, Los Angeles, has now found that males and females show differences in the expression of no fewer than 50 genes well before SRY switches on," according to the magazine.

Eric Vilain, the head of the UCLA team, said three of the genes are dominant in females and four in males, but they still need to determine whether the genes influence brain sexuality in mice and whether the same thing occurs in humans.

You can find the same article here.

Eric Vilain's home page at UCLA provides some more details about his lab's work:

Sex determination orients development toward sexually dimorphic individuals, male or female. In mammals, male sex determination is triggered by a primary signal, encoded by the testis determining factor SRY, localized on the Y chromosome. Subsequently, a complex network of genes, most of them still unknown, is regulated and leads to male sexual differentiation. We have discovered new molecular and cellular mechanisms of sex determination during fetal development. In particular, we have provided strong evidence supporting SRY as the testis determining gene, and identified regulatory mechanisms of transcription of DAX1, another sex determining gene. We have also recently identified human WNT-4, a signalling molecule responsible, when duplicated, for XY sex reversal in mammals. A new concept is now emerging: normal sexual development is highly dependent on strict gene dosage at all major steps of the sex determination pathway.

One possibility this opens up is the ability to separately control genital and brain sexual differentiation. Some day there will be people who have male minds in female bodies and vice versa. They will be more like the opposite sex in their thinking than is the case with homosexuals.

By Randall Parker    2002 October 19 02:14 PM   Entry Permalink | Comments (8)
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