2012 June 20 Wednesday
Scientists Block Mouse Rage

Scared by violent mice? Live in fear of murine madness? Scientists have found a way to block mouse rage.

Pathological rage can be blocked in mice, researchers have found, suggesting potential new treatments for severe aggression, a widespread trait characterized by sudden violence, explosive outbursts and hostile overreactions to stress.

Blocking the receptor NMDA moderates mouse aggression. A drug that targets NMDA in humans might cut human aggression as well.

In a study appearing today in the Journal of Neuroscience, researchers from the University of Southern California and Italy identify a critical neurological factor in aggression: a brain receptor that malfunctions in overly hostile mice. When the researchers shut down the brain receptor, which also exists in humans, the excess aggression completely disappeared.

The findings are a significant breakthrough in developing drug targets for pathological aggression, a component in many common psychological disorders including Alzheimer's disease, autism, bipolar disorder and schizophrenia.

Suppose a gene therapy gets developed that will so reduce NMDA receptor activity that violent prisoners could have their chances of committing violent acts reduced by a few orders of magnitude. Would you favor use of the NMDA-blocking gene therapy as a condition for parole of a violent felon?

By Randall Parker    2012 June 20 09:26 PM   Entry Permalink | Comments (3)
2012 January 16 Monday
Mathematical Power Law For Serial Killer Behavior

The Technology Review Arxiv blog has an interest post about how a Russian serial killer's frequency of killing fits a power law that suggests a pattern of neuronal recharge after killings.

On 20 November 1990, Andrei Chikatilo was arrested in Rostov, a Russian state bordering the Ukraine. After nine days in custody, Chikatilo confessed to the murder of 36 girls, boys and women over a 12 year period. He later confessed to a further 20 murders, making him one of the most prolific serial killers in modern history.

Today, Mikhail Simkin and Vwani Roychowdhury at the University of California, Los Angeles, release a mathematical analysis of Chikatilo's pattern of behaviour. They say the behaviour is well characterised by a power law and that this is exactly what would be expected if Chikatilo's behaviour is caused by a certain pattern of neuronal firing in the brain.

Click thru and read it to see if you find their conclusion likely. It seems plausible to me. Here's the abstract.

What I'd like to know: Short of committing a real murder how to drain the neural excitation that initiates a serial killer's desire to kill? On a related note: Has the playing of violent video games reduced the frequency of killing by serial killers? Could we detect the draining effects of simulated kills in video games by looking for signs of lower frequency of serial killing over the last 20 years?

What would really help: better ways to detect serial killers: What sorts of measurements could detect a person's propensity to become a serial killer? I've been reading a number of books lately about psychological research (e.g. Daniel Kahnemann's excellent Thinking Fast And Slow) and am struck by tricky means psychologists have devised for measuring cognitive phenomena. For example, pupil dilation happens and can be usefully measured when the conscious brain is thinking hard. Can any existing tools of psychological and neurobiological research show differences between serial killers and the population at large?

We need the ability to detect serial killers in advance. How to get from the idea that neurons charge up to activate serial killing circuitry to a way to more rapidly detect serial killers in our midst? Ideas?

By Randall Parker    2012 January 16 07:41 PM   Entry Permalink | Comments (7)
2012 January 01 Sunday
Epilepsy Connection To Violent Crime Risk?

Some Swedish and British researchers question the supposed link between epilepsy and violent crime.

Despite current public and expert opinion to the contrary, having the neurological condition epilepsy is not directly associated with an increased risk of committing violent crime. However, there is an increased risk of individuals who have experienced previous traumatic brain injury going on to commit violent crime according to a large Swedish study led by Seena Fazel from the University of Oxford, UK, and colleagues at the Karolinska Institutet, Sweden, and Swedish Prison and Probation Service, and published in this week's PLoS Medicine.

The authors say: "The implications of these findings will vary for clinical services, the criminal justice system, and patient charities."

In their study, the authors identified all people with epilepsy and traumatic brain injury recorded in Sweden between 1973 and 2009 and matched each case with ten people without these brain conditions from the general population. The investigators linked these records to subsequent data on all convictions for violent crime using the personal identification numbers that identify Swedish residents in national registries.

Sweden's extensive record keeping on its populace sure comes in handy for scientific research.

I don't think these results mean what these researchers think they mean. Just because other non-epileptic family members of epileptics have the same increased risk of violent crime does not mean that epileptics aren't at increased risk of committing violent crime.

Using these methods, the authors found that 4.2% of people with epilepsy had at least one conviction for violence after their diagnosis compared to 2.5% of the general population. However, after controlling for the family situation (in which individuals with epilepsy were compared with their unaffected siblings), the association between being diagnosed with epilepsy and being convicted for violent crime disappeared.

A plausible explanation: genetic variants that increase the risk of developing epilepsy also boost the risk of crime regardless of whether they cause epilepsy in their carriers. Though even if some genetic variants contribute to epilepsy risk and violence that does not mean that all genetic variants that contribute to one also contribute to the other. Also, even if some genetic variant contributes to both epilepsy and violence that does not mean that variant increases the risk of violent crime in all carriers. Other genetic variants elsewhere in the genome could cancel out violent crime risks in some carriers. The interactions between human brain genes are going to be enormously difficult to discover and model.

Traumatic brain injury is linked to higher risk of committing violent crime. There ar4e plausible mechanisms of causation in both directions. Obviously brain damage could harm brain circuitry that restrains behavior or it could enhance anger that people feel when insulted or could work via some other mechanism to make violent acts more likely. Though people who are violent in the first place are at greater risk of getting their brains beaten on in a fight or damaged in a road rage incident. The full research paper (linked in the first paragraph) even mentions that brain trauma is common in prison.

In contrast, the authors found that after controlling for substance abuse or comparing individuals with brain injury to their unaffected siblings, there remained an association between experiencing a traumatic brain injury and committing a violent crime.

Given the high incidence of traumatic brain injury from improvised explosive devices (IEDs) among US military veterans that served in Iraq and Afghanistan some of these veterans might be at greater risk of violence as a result.

The full paper even mentions that some subtypes of epilepsy are associated with a reduced risk of violent crime.

By Randall Parker    2012 January 01 11:04 PM   Entry Permalink | Comments (1)
2011 February 09 Wednesday
Child Aggression Driven By Status Hierarchy Position

Kids near the top do the most tormenting while kids at the top do the least. Once you reach the top you can kick back and let those below you fight it out.

While experts often view aggressive behavior as a maladjusted reaction typical of social outcasts, a new study in the February issue of the American Sociological Review finds that it’s actually popular adolescents—but not the most popular ones—who are particularly likely to torment their peers.

“Our findings underscore the argument that—for the most part—attaining and maintaining a high social status likely involves some level of antagonistic behavior,” said Robert Faris, an assistant professor of sociology at the University of California-Davis.

The study, which Faris co-authored with sociology professor Diane Felmlee, his UC-Davis colleague, also finds that those students in the top 2% of the school social hierarchy—along with those at the bottom—are the least aggressive.

You might want to exist outside of dominance hierarchies. But with rising populations and rapid transportation and communications it is hard to escape from them.

By Randall Parker    2011 February 09 12:32 AM   Entry Permalink | Comments (21)
2010 December 24 Friday
Serotonin Gene Variant With Alcohol Makes Men Violent

The HTR2B variant of a serotonin neurotransmitter receptor in the brain makes Finnish men violent if they drink. The HTR2B variant occurs at a much higher rate in violent felons.

A multinational research team led by scientists at the National Institutes of Health has found that a genetic variant of a brain receptor molecule may contribute to violently impulsive behavior when people who carry it are under the influence of alcohol. A report of the findings, which include human genetic analyses and gene knockout studies in animals, appears in the Dec. 23 issue of Nature.

"Impulsivity, or action without foresight, is a factor in many pathological behaviors including suicide, aggression, and addiction," explains senior author David Goldman, M.D., chief of the Laboratory of Neurogenetics at the NIH’s National Institute on Alcohol Abuse and Alcoholism (NIAAA). "But it is also a trait that can be of value if a quick decision must be made or in situations where risk-taking is favored."

This is an example of why it is valuable for individuals to get their genomes tested. Direct-to-consumer genetic testing ought to be available without regulatory barriers in the way (please tell the FDA and the California and NY state governments). Whether you carry a genetic variant that is liable to make you violent under the influence of alcohol is knowledge that teenagers ought to know. It could save lives, prevent maiming, and keep our prisons less crowded.

Scientists will discover all the genetic variants that make some people dangerous when drunk. I say the sooner the better.

"Interestingly, we found that the genetic variant alone was insufficient to cause people to act in such ways," notes Dr. Goldman. "Carriers of the HTR2B variant who had committed impulsive crimes were male, and all had become violent only while drunk from alcohol, which itself leads to behavioral disinhibition."

The researchers also found that knocking out this gene in mice caused the mice to become more impulsive. The researchers are currently trying to determine whether alcohol makes those mice even more impulsive. Obviously, this could lead to a genetic test to determine whether it is safe to let your pet mouse drink alcohol.

Other genetic variants that increase impulsive and violent behavior are likely to be found.

"Although relatively common in Finland, the genetic variant we identified in this study is unlikely to explain a large fraction of the overall variance in impulsive behaviors, as there are likely to be many pathways to impulsivity in its various manifestations," says Dr. Goldman.

Sounds like about 5 percent of Finnish violent felons might not be in jail if they never drank alcohol.

They found that 7.46% of the violent offenders had the mutation, compared with 2.32% of controls.

By Randall Parker    2010 December 24 11:46 PM   Entry Permalink | Comments (4)
2010 June 07 Monday
3 Traits Key To Higher Violence From Video Games

Neurotic, less agreeable, and unconscientious kids are most likely to be made more violent from playing video games.

WASHINGTON – Playing violent video games can make some adolescents more hostile, particularly those who are less agreeable, less conscientious and easily angered. But for others, it may offer opportunities to learn new skills and improve social networking.

In a special issue of the journal Review of General Psychology, published in June by the American Psychological Association, researchers looked at several studies that examined the potential uses of video games as a way to improve visual/spatial skills, as a health aid to help manage diabetes or pain and as a tool to complement psychotherapy. One study examined the negative effects of violent video games on some people.

"Much of the attention to video game research has been negative, focusing on potential harm related to addiction, aggression and lowered school performance," said Christopher J. Ferguson, PhD, of Texas A&M International University and guest editor of the issue. "Recent research has shown that as video games have become more popular, children in the United States and Europe are having fewer behavior problems, are less violent and score better on standardized tests. Violent video games have not created the generation of problem youth so often feared."

So some kids are made more hostile and violent by playing video games. But most kids are made less violent by playing video games or are unchanged by the experience.

Some day genetic analyses, personality tests, and other assessments will be used to choose custom environments best suited for each kid. Though only the most agreeable and conscientious parents will be good about keeping their kids immersed in their personal ideal environments. Some disagreeable parents will put their kids into environments opposite of what experts recommend. So then social workers will try to anticipate this reaction and recommend environments the opposite of what the kids need.

By Randall Parker    2010 June 07 11:02 PM   Entry Permalink | Comments (2)
2009 August 04 Tuesday
Psychopath Brain Different In Brain Scans

Psychopathy is seen by some researchers as having a biological cause in the brain.

Professor Declan Murphy and colleagues Dr Michael Craig and Dr Marco Catani from the Institute of Psychiatry at King's College London have found differences in the brain which may provide a biological explanation for psychopathy. The results of their study are outlined in the paper 'Altered connections on the road to psychopathy', published in Molecular Psychiatry.

The research investigated the brain biology of psychopaths with convictions that included attempted murder, manslaughter, multiple rape with strangulation and false imprisonment. Using a powerful imaging technique (DT-MRI) the researchers have highlighted biological differences in the brain which may underpin these types of behaviour and provide a more comprehensive understanding of criminal psychopathy.

Some people are bad to the bone. Or perhaps bad to the uncinate fasciculus. Brain scans of the uncinate fasciculus (UF) found distinct differences in psychopaths.

Earlier studies had suggested that dysfunction of specific brain regions might underpin psychopathy. Such areas of the brain were identified as the amygdale, ie the area associated with emotions, fear and aggression, and the orbitofrontal cortex (OFC), the region which deals with decision making. There is a white matter tract that connects the amygdala and OFC, which is called the uncinate fasciculus (UF). However, nobody had ever studied the UF in psychopaths. The team from King's used an imaging method called in vivo diffusion tensor magnetic resonance imaging (DT-MRI) tractography to analyse the UF in psychopaths.

They found a significant reduction in the integrity of the small particles that make up the structure of the UF of psychopaths, compared to control groups of people with the same age and IQ. Also, the degree of abnormality was significantly related to the degree of psychopathy. These results suggest that psychopaths have biological differences in the brain which may help to explain their offending behaviours.

By Randall Parker    2009 August 04 10:21 PM   Entry Permalink | Comments (25)
2008 November 08 Saturday
Brain Scans Show Bullies Enjoy Seeing Others Suffer

Okay puppets, who among you are sadists? Some people are wired up with a puppeteer in their brains that makes them enjoy seeing pain in others. Sadists are wired up to be sadists.

Unusually aggressive youth may actually enjoy inflicting pain on others, research using brain scans at the University of Chicago shows.

Scans of the aggressive youth's brains showed that an area that is associated with rewards was highlighted when the youth watched a video clip of someone inflicting pain on another person. Youth without the unusually aggressive behavior did not have that response, the study showed.

"This is the first time that fMRI scans have been used to study situations that could otherwise provoke empathy," said Jean Decety, Professor in Psychology and Psychiatry at the University of Chicago. "This work will help us better understand ways to work with juveniles inclined to aggression and violence."

Some kids are just bad to the bone. Once it becomes possible to precisely identify such kids I expect some private schools to reject them as applicants. Though in some jurisdictions governments will try to prevent the screening out of bullies.

The youth were tested with fMRI while looking at video clips in which people endured pain accidentally, such as when a heavy bowl was dropped on their hands, and intentionally, such as when a person stepped on another's foot.

"The aggressive youth activated the neural circuits underpinning pain processing to the same extent, and in some cases, even more so than the control participants without conduct disorder," Decety said.

"Aggressive adolescents showed a specific and very strong activation of the amygdala and ventral striatum (an area that responds to feeling rewarded) when watching pain inflicted on others, which suggested that they enjoyed watching pain," he said.

Unlike the control group, the youth with conduct disorder did not activate the area of the brain involved in self-regulation (the medial prefrontal cortex and the temporoparietal junction).

I bet people who have committed murder are more likely to show this brain activation pattern than law-abiding people. So them could brain implants be devised that will block these feelings of pleasure from pain?

By Randall Parker    2008 November 08 05:22 PM   Entry Permalink | Comments (7)
2008 September 30 Tuesday
Antisocial Kids Have Less Cortisol In Stressful Situations

The juvenile delinquent kids going down the wrong path maybe act bad due to endocrine system deficiencies in cortisol production.

A link between reduced levels of the 'stress hormone' cortisol and antisocial behaviour in male adolescents has been discovered by a research team at the University of Cambridge.

Levels of cortisol in the body usually increase when people undergo a stressful experience, such as public speaking, sitting an exam, or having surgery. It enhances memory formation and is thought to make people behave more cautiously and to help them regulate their emotions, particularly their temper and violent impulses.

So suppose we could come up with a nanosensor that measured when some violent guy was about to act aggressively. Imagine combining that with some nanocomputer and a little nanotube network tied to some cells that can be stimulated to excrete cortisol. Implant all that into the body of someone with violent impulses and it should be possible to cut back on their violent outbursts. What do you think? Want safer streets via tech that controls people? We are maybe about 10 years away from being able to do this sort of thing.

I'd like to know which sorts of antisocial kids don't produce as much cortisol. Do some of them lack the ability to see a situation as stressful?

The new research, funded by the Wellcome Trust, shows that adolescents with severe antisocial behaviour do not exhibit the same increase in cortisol levels when under stress as those without antisocial behaviour. These findings suggest that antisocial behaviour, at least in some cases, may be seen as a form of mental illness that is linked to physiological symptoms (involving a chemical imbalance of cortisol in the brain and body).

The scientists, led by Dr Graeme Fairchild and Professor Ian Goodyer, recruited participants for the study from schools, pupil referral units, and the Youth Offending Service. Samples of saliva were collected over several days from the subjects in a non-stressful environment to measure levels of the hormone under resting conditions. The young men then took part in a stressful experiment that was designed to induce frustration. Samples of saliva were taken immediately before, during and after the experiment to track how cortisol changed during stress.

The differences between participants with severe antisocial behaviour and those without were most marked under stressful conditions. While the average adolescents showed large increases in the amount of cortisol during the frustrating situation, cortisol levels actually went down in those with severe antisocial behaviour.

So are these kids this way because of genetic reasons, responses to experiences, or some combination thereof? Maybe the bad kids have become desensitized to stress? Or maybe their ability to get violent in stressful situation was an adaptive advantage for their ancestors and contributing genes got selected for.

Some kids go bad with depressed cortisol levels at age 5. Pity the parents - unless they too have depressed cortisol levels and are terrors.

One other surprise was that the cortisol drops were about the same across all the delinquents, whether they originally became disruptive during childhood or during adolescence.

Although it's already accepted that there is a strong biological component to "early-onset" conduct disorder, which develops around the age of five, the current thinking is that when delinquency develops in teenagers, it's mainly a result of malevolent peer pressure, perhaps combined with lack of supervision at home.

The new research challenges this picture by showing that in both groups, cortisol levels fell – a biological rather than peer-led response.

Implanted devices that release cortisol would be like an artificial endocrine system that makes up for underactive adrenal glands.

By Randall Parker    2008 September 30 11:15 PM   Entry Permalink | Comments (6)
2006 October 01 Sunday
High Testosterone Men More Abusive To Dogs

Testosterone leads to dog abuse.

Robert Josephs, associate professor of psychology, and Amanda Jones, graduate student, examined how testosterone levels influence pet owners’ behavior and, in turn, how they affect the hormonal changes in their animals during stressful situations.

Their findings appear in a paper titled “Interspecies Hormonal Interactions Between Man and the Domestic Dog” in the current issue of Hormones and Behavior, a biology journal.

The researchers found men’s testosterone levels determined their behavior toward their dogs, after the dogs performed poorly in a statewide agility competition. Men with high levels of testosterone punished their dogs by hitting them and yelling at them whereas men with lower levels supported their dogs by petting and praising the losing animals.

The response of these men is probably counterproductive. The abuse causes brain damage that inhibits memory formation. Therefore learning is impaired and the dogs become less likely to learn the lessons they need to excel.

Punished dogs showed an alarming rise in the stress hormone cortisol, a neurotoxic substance that can lead to destruction of cells in the hippocampus, leading to memory deficits. Chronically elevated cortisol levels also weaken the immune system. These consequences might be especially critical for dogs in high stress jobs in which memory and health are critical, such as bomb-sniffing, police and guide dog environments.

Although there is much research demonstrating how changes in an individual’s hormone levels influence behavior toward another individual of the same species, this is the first research to examine effects across the species boundary.

I've had a couple of bosses who suffered from testosterone toxicity. They also exerted counterproductive effects on the workplace. Competitiveness and drive help to a point. But these drives have to be coupled to strong discipline and a considerable amount of wisdom or else the aggressiveness just destroys.

Anyway, I feel sorry for these abused dogs. Guys who hit a dog for failing to do well in agility training ought to go find a sport that forces them to perform rather than torture dogs into performing.

When genetic engineering of offspring becomes possible will the average male baby get genetically engineered to have higher or lower testosterone than happens now naturally? Will parents want to have assertive, athletic, and dominant sons and therefore opt for more testosterone?

By Randall Parker    2006 October 01 11:11 AM   Entry Permalink | Comments (5)
2006 June 06 Tuesday
Intermittent Explosive Disorder More Prevalent Than Suspected

We live among lots of dangerous people.

A little-known mental disorder marked by episodes of unwarranted anger is more common than previously thought, a study funded by the National Institutes of Health's (NIH) National Institute of Mental Health (NIMH) has found. Depending upon how broadly it's defined, intermittent explosive disorder (IED) affects as many as 7.3 percent of adults — 11.5-16 million Americans — in their lifetimes. The study is based on data from the National Comorbidity Survey Replication, a nationally representative, face-to-face household survey of 9,282 U.S. adults, conducted in 2001-2003.

I bet these people with IED will eventually be identifiable with brain scans. Suppose a treatment to stop IED is developed. Will future societies support mandatory delivery of therapies that prevent violent episodes?

People with IED have other mental problems.

People with IED may attack others and their possessions, causing bodily injury and property damage. Typically beginning in the early teens, the disorder often precedes — and may predispose for — later depression, anxiety and substance abuse disorders. Nearly 82 percent of those with IED also had one of these other disorders, yet only 28.8 percent ever received treatment for their anger, report Ronald Kessler, Ph.D., Harvard Medical School, and colleagues. In the June, 2006 Archives of General Psychiatry, they suggest that treating anger early might prevent some of these co-occurring disorders from developing.

To be diagnosed with IED, an individual must have had three episodes of impulsive aggressiveness "grossly out of proportion to any precipitating psychosocial stressor," at any time in their life, according to the standard psychiatric diagnostic manual. The person must have "all of a sudden lost control and broke or smashed something worth more than a few dollars…hit or tried to hurt someone…or threatened to hit or hurt someone."

People who had three such episodes within the space of one year — a more narrowly defined subgroup — were found to have a much more persistent and severe disorder, particularly if they attacked both people and property. The latter group caused 3.5 times more property damage than other violent IED sub-groups. Affecting nearly 4 percent of adults within any given year — 5.9-8.5 million Americans — the disorder leads to a mean of 43 attacks over the course of a lifetime and is associated with substantial functional impairment.

Evidence suggests that IED might predispose toward depression, anxiety, alcohol and drug abuse disorders by increasing stressful life experiences, such as financial difficulties and divorce

Once we achieve the ability to reverse aging using SENS techniques the existence of people who are capable of explosive anger and physical attacks will be viewed as a much bigger threat due to the length of individual lives. A person who goes overboard in their reactions when they get angry is more likely to kill someone if they have centuries more to do so. If we live for thousands of years each of us will face a much larger risk of eventually getting murdered.

In an era when aging becomes fully reversible I expect we will witness movements to create new nations that have extremely selective immigration policies designed to keep out people with violent tendencies. New polities will be created by long livers who want to minimize their risk of death. Such polities will also implement very high safety standards.

By Randall Parker    2006 June 06 10:31 PM   Entry Permalink | Comments (8)
2005 March 04 Friday
Index And Ring Finger Lengths Partially Predict Violent Tendencies

Higher prenatal testosterone has already been found to be correlated with a higher ratio of ring finger length to index finger length. Now University of Alberta researchers Peter Hurd and Allison Bailey have shown that the higher ring finger to index finger ratio is correlated with physically aggressive behavior in men.

Dr. Peter Hurd initially thought the idea was "a pile of hooey", but he changed his mind when he saw the data.

Hurd and his graduate student Allison Bailey have shown that a man's index finger length relative to ring finger length can predict how inclined that man is to be physically aggressive. Women do not show a similar effect.

A psychologist at the University of Alberta, Hurd said that it has been known for more than a century that the length of the index finger relative to the ring finger differs between men and women. More recently, researchers have found a direct correlation between finger lengths and the amount of testosterone that a fetus is exposed to in the womb. The shorter the index finger relative to the ring finger, the higher the amount of prenatal testosterone, and--as Hurd and Bailey have now shown--the more likely he will be physically aggressive throughout his life.

"More than anything, I think the findings reinforce and underline that a large part of our personalities and our traits are determined while we're still in the womb," said Hurd.

Hurd and Bailey's research, published this March in Biological Psychology, was determined from surveys and hand measurements of 300 U of A undergraduates.

In their study, they found there were no correlations between finger lengths and people who are prone to exhibit verbally aggressive, angry, or hostile behaviors, but there was to physically aggressive behavior.

Hurd is conducting ongoing research in this area, including a study that involves measuring hockey players' finger lengths and cross referencing the results with each player's penalty minutes. He also has a similar study showing that men with more feminine finger ratios are more prone to depression; a paper on this will be published later this year in Personality and Individual Differences.

"Finger lengths explain about five per cent of the variation in these personality measures, so research like this won't allow you to draw conclusions about specific people. For example, you wouldn't want to screen people for certain jobs based on their finger lengths," Hurd said. "But finger length can you tell you a little bit about where personality comes from, and that's what we are continuing to explore."

Every year that goes by more of human behavior is going to be pinned down to biological causes. Mechanisms of operation of each cause will be worked out down at the molecular level. This is going to be quite the challenge to mainstream Western liberal thought and to at least some schools of Christian theology (though perhaps not to those who believe in predestination) as the ghost is shown to have progressively less operating leeway within the machine.

Are you a male that is worried you have too much testosterone that is making you too aggressive? Get married and have kids and your blood testosterone will go down. On the other hand, if you want that aggressive edge and really good visual-spatial abilities then either eschew marriage or wear a testosterone patch. Not that I'm advocating hormone dosing...

By Randall Parker    2005 March 04 08:59 AM   Entry Permalink | Comments (24)
2004 October 04 Monday
Stress And Violence Feed Back In Vicious Cycle

Hormonal and neural chances caused by stress and aggression feed back on each other and promote each other.

WASHINGTON -- Scientists may be learning why it's so hard to stop the cycle of violence. The answer may lie in the nervous system. There appears to be a fast, mutual, positive feedback loop between stress hormones and a brain-based aggression-control center in rats, whose neurophysiology is similar to ours. It may explain why, under stress, humans are so quick to lash out and find it hard to cool down. The findings, which could point to better ways to prevent pathological violence, appear in the October issue of Behavioral Neuroscience, which is published by the American Psychological Association (APA).

In five experiments using 53 male rats, behavioral neuroscientists from the Netherlands and Hungary studied whether stimulating the brain's aggression mechanism raised blood levels of a stress hormone and whether higher levels of the same hormone led to the kind of aggression elicited by that mechanism. The results showed a fast-acting feedback loop; the mechanism works in both directions and raising one variable raises the other. Thus, stress and aggression may be mutually reinforcing, which could explain not only why something like the stress of traffic jams leads to road rage, but also why raging triggers an ongoing stress reaction that makes it hard to stop.

In the study, the scientists electrically stimulated an aggression-related part of the rat hypothalamus, a mid-brain area associated with emotion. The rats suddenly released the stress hormone corticosterone (very like cortisol, which humans release under stress) -- even without another rat present. Normally, rats don't respond like that unless they face an opponent or another severe stressor.

Says lead author Menno Kruk, PhD, "It is well known that these stress hormones, in part by mobilizing energy reserves, prepare the physiology of the body to fight or flee during stress. Now it appears that the very same hormones 'talk back' to the brain in order to facilitate fighting."

To study the hypothesized feedback loop from the other direction, the scientists removed the rats' adrenal glands to prevent any natural release of corticosterone. Then researchers injected the rats with corticosterone. Within minutes of injection, the hormone facilitated stimulation-evoked attack behavior.

Thus, in rapid order, stimulating the hypothalamic attack area led to higher stress hormones and higher stress hormones led to aggression – evidence of the feedback loop within a single conflict. Write the authors, "Such a mutual facilitation may contribute to the precipitation and escalation of violent behavior under stressful conditions."

They add that the resulting vicious cycle "would explain why aggressive behavior escalates so easily and is so difficult to stop once it has started, especially because corticosteroids rapidly pass through the blood-brain barrier." The findings suggest that even when stress hormones spike for reasons not related to fighting, they may lower attack thresholds enough to precipitate violent behavior. That argument, if extended in research to humans, could ultimately explain on the biological level why a bad day at the office could prime someone for nighttime violence toward family members.

Stress reaction is one of the evolutionary legacies of human evolution that in modern conditions is mostly maladaptive. Most people who get angry or frustrated and therefore feel stress are not benefitting and are even being harmed by the stress. We need better biotechnological tools for suppressing stress response. This would do more than reduce the incidence of acts of violence. Heart disease, general aging, depression, and other maladies would occur less frequently if stress responses happened less often.

Regarding my previous post on car cruise controls and automated driving: One of the benefits of being able to turn driving over to computers would be a reduction in feelings of stress. The stress of fighting commuter traffic comes on top of stresses associated with work and home life. Lower levels of stress made possible by automated driving computers would reduce both illness and violence.

By Randall Parker    2004 October 04 12:25 PM   Entry Permalink | Comments (5)
2004 August 20 Friday
People With Asymmetric Bodies More Aggressive?

Beware people with uneven body shapes.

Research showed that the farther certain paired body parts were from symmetry – if one ear, index finger or foot was bigger than another, for example – the more likely it is was that a person would show signs of aggression when provoked. The symmetry effects were different in men and women, however.

While the findings may seem strange, there is a plausible explanation, said Zeynep Benderlioglu, co-author of the study and a post-doctoral researcher at Ohio State University.

The physical attraction people have to highly symmetrical faces in the opposite sex is very likely the product of natural selection. The symmetry is a sign of health and reproductive fitness. This latest study shows that asymmetry is even a proxy for a tendency toward impulsiveness.

Body asymmetry is thought to be an indicator that the fetus was under stress (e.g. toxins, nutrient deficiencies or perhaps more stress hormones released by the mother) during development. The visible physical asymmetry is thought to be a proxy for malformations of other less visble parts of the body including the brain.

The study involved 100 college students (51 men and 49 women). Researchers measured differences in size of several paired body parts, including finger length, palm height, wrist diameter, elbow width, ear height and width, foot breadth and ankle circumference. The sum of all the differences in these pairs gave researchers a score of asymmetry for each participant.

The students, who were all volunteers, were told they were going to participate in a study of persuasive ability. They were given a list of phone numbers to call and attempt to raise funds for a fictitious charity organization. But they were actually calling two people involved in the study who were given instructions about how to respond to the study participants.

One of the people the participants called seemed friendly and amenable to giving, but said he didn’t have money to donate. But the second charity target was confrontational. He directly challenged the caller and the worthiness of the donation.

The researchers had rigged the phones so they could measure how hard the participants slammed the receiver down after the call – this was a measure of reactive aggression.

Results showed that, in general, the more asymmetry the participants showed in their body parts, the more force they used when hanging up the phone.

But there were also interesting gender differences.

In men, asymmetry was related to a more aggressive response when ending the phone call under the low-provocation condition – when the person simply didn’t have money to give. But there was no such association between asymmetry and aggression in the high-provocation condition -- when they talked with the rude charity target.

For women, it was just the opposite – there was no relation between asymmetry and aggression with the low-provocation caller, but women with higher asymmetry scores used more force when hanging up from the rude, high-provocation caller.

Benderlioglu said these results probably have to do with the different ways men and women respond to provocation in general.

“Research has shown that men are quicker to anger than are women,” she said. “But while unprovoked men are generally more aggressive than women, the gender differences either disappear under provocation, or women may actually become more aggressive than men.”

High testosterone made men more angry during low-provocation phone calls. But the opposite was the case with women.

Men with high levels of testosterone used more force when slamming down the phone only under the low-provocation condition. In women, higher levels of testosterone were associated with higher aggressiveness only under the high-provocation condition.

One of the most interesting twists is that confrontational behavior does not always elicit an aggressive response. But this makes sense intuitively. In many situations a person who shows fear is more likely to be attacked than a person who acts menacingly.

Update: Also see my related post Premature Birth Produces More Lasting Brain Effects In Boys. Factors that cause less than optimal conditions during pregnancies have the potential of creating behavior problems that will endure for life. Drug abuse, malnutrition, physical abuse of pregnant women, and other stressors on developing fetuses exact a very long term cost to society as a whole.

By Randall Parker    2004 August 20 04:56 PM   Entry Permalink | Comments (7)
2004 May 04 Tuesday
Soy Isoflavones Make Male Monkeys Aggressive

Beware of mad killer tofu.

People have the concept that soy is only beneficial, said Jay R. Kaplan, Ph.D., professor of comparative medicine and anthropology, one of the investigators. "There is the thought that what is good for some is good for all and more is better."

But this research points out that not only does the dose make a difference, but so does the sex of the consumer, Kaplan said, adding that the study is consistent with emerging literature showing that soy can have a negative impact on the behavior of male rodents. Previous studies have shown no difference in aggression in females given large doses of soy, Kaplan said.

The study was done over 15 months with adult male monkeys who were divided into three groups and fed different amounts and types of protein. One group had about 125 mg of isoflavones a day. The second group had half that amount, and the third group's protein came from milk and animal sources.

"In the monkeys fed the higher amounts of isoflavones, frequencies of intense aggressive and submissive behavior were elevated," according to the study. "In addition, the proportion of time spent by these monkeys in physical contact with other monkeys was reduced by 68 percent, time spent in proximity to other monkeys was reduced 50 percent and time spent alone was increased 30 percent."

Isoflavone levels of 125 mg per day are higher than amounts consumed by many Asians, who typically eat more soy than other populations. But, the isoflavone levels are comparable to levels found in many dietary supplements sold in the United States.

The fact that it increases both aggressive and submissive behavior is curious. Did it increase aggression in some monkeys and submission in others? Or was it a function of circumstance with the same monkeys showing more of each behavior?

Steroid use by athletes causes violent outbursts popularly known as "roid rage". Does the combination of soy and steroids act synergistically to produce even more violent behavior?

Will gang members or other deviants start using isoflavones in order to make themselves more aggressive?

By Randall Parker    2004 May 04 10:38 AM   Entry Permalink | Comments (2)
2004 April 25 Sunday
Humans Most Violent When Only 2 Years Old

An excellent article by Erin Anderssen and Anne McIlroy in the Canadian Globe And Mail summarizes research on child development and human violence. They report that Richard Tremblay has found that 2 year old babies are more physically aggressive than teenagers or adults but fortunately too uncoordinated to do much damage to others.

Are human beings born pure, as Rousseau argued, and tainted by the world around them? Or do babies arrive bad, as St. Augustine wrote, and learn, for their own good, how to behave in society?

Richard Tremblay, an affable researcher at the University of Montreal who is considered one of the world leaders in aggression studies, sides with St. Augustine, whom he is fond of quoting.

Dr. Tremblay has thousands of research subjects, many studied over decades, to back him up: Aggressive behaviour, except in the rarest circumstances, is not acquired from life experience. It is a remnant of our evolutionary struggle to survive, a force we learn, with time and careful teaching, to master. And as if by some ideal plan, human beings are at their worst when they are at their weakest.

St. Augustine was obviously much closer to the truth.

What Dr. Tremblay and his colleagues around the world have now demonstrated is that the ability to feel rage exists the moment human beings take their first breaths. A four-month-old infant can show anger. And as they gain more control over their arms and legs, their mothers report increasing incidents of kicking and biting: They can also act in anger.

By the second year, aggressive behaviour peaks in temper tantrums, with slapping and pushing; according to Dr. Tremblay's work, a typical two-year-old, playing with others over the course of an hour, will commit one act of physical aggression for every four social interactions.

With teenagers, he says, researchers talk in terms of years or months or weeks between aggressive acts -- never hours -- though the incidents, obviously, are more severe. By their third birthdays, children have the motor skills to perform any of the acts of aggression an adult can. But at just that age, aggression begins to drop.

For almost everyone, it continues to drop for the rest of their lives. By Dr. Tremblay's calculation, only in about 5 per cent of men does the rate of aggression remain relatively stable into early adulthood. They are the most dangerous group to society.

The article tries to put what I consider to be an excessive environmental spin on the reason for the decline in physical aggression as children age. The fact that babies simultaneously become more physically coordinated and less violent at the same time strikes me as too much of a coincidence to be the result of teaching and discipline. Likely there is a genetically programmed stage of mental development that builds inhibiting neural circuits to control the physical outbursts.

The article vaguely refers to a study on the genetic and environmental factors that cause children to grow up to be antisocial. That is probably a reference to a New Zealand twins study which showed that a combination of a genetic variant for low level of expression of Mono-Amine Oxidase A (MAOA) and childhood abuse produces much higher rates of adolescent and adult criminal violence. However, contrary to Anderssen and McIlroy the study did not show that both the environmental and genetic factors studied had to be present to result in violence. It is just that those two factors made children far more prone to grow up to be violent. Some children who were not abused still grew up to be violent. Similarly, some children who expressed MAOA at a high level still grew up to be violent as well. There may be still more as yet unknown genetic variations, nutritional factors, toxins, social environmental factors, and other factors which contribute to higher probability of violent behavior.

The article also refers to Adrian Raine's work using positron emission tomography (PET) scans that showed differences in the glucose consumption rates in the brains of murderers.

For the Biological Psychiatry study, Dr. Raine directed scientists at USC and the University of California at Irvine as they used positron emission tomography (PET) to scan the brains of 41 murderers who had pleaded not guilty by reason of insanity. The scientists also scanned the brains of 41 control subjects matched for known mental disorders and for age and gender. Mental disorders among the subjects included schizophrenia, organic brain damage and a history of head injury.

PET scans measure the uptake of blood sugar (glucose) in various brain areas during the performance of simple, repetitive tasks. (Glucose is the basic fuel that powers most cell functions. The amount used is directly related to the amount of cell activity.)

On average, the murderers showed significantly lower rates of glucose uptake in three areas of the brain -- the prefrontal cortex, the corpus callosum and the posterior parietal cortex. Their rates were 4, 18 and 4 percentage points lower, respectively, than the rates measured in control subjects performing the same tasks.

When the researchers compared the brain's two hemispheres for glucose uptake rates, they found that murderers consistently showed weaker activity in the amygdala and the hippocampus of the brain's left -- or more rational -- hemisphere. These glucose uptake rates were each 4 percentage points lower than the rates measured in control subjects performing the same tasks.

But the murderers showed stronger activity in the thalamus, the amygdala, and the hippocampus of the right -- or more emotional -- hemisphere. These glucose uptake rates were 6, 6 and 3 percentage points higher, respectively, than the rates measured in control subjects performing the same tasks.

Raine has also shown that psychopaths have distinct differences in the shapes of some parts of their brains and that violent criminals have less brain gray matter.

These discoveries add up to suggest that there are limits to how much violent tendencies can be reduced using environmental changes and different methods of teaching and disciplining children. It seems unlikely that methods of teaching and socialization can fully compensate for less grey matter in those who commit violent acts as adults or the larger corpus callosums and asymmetrical hypothalamuses found in psychopaths.

By Randall Parker    2004 April 25 12:31 AM   Entry Permalink | Comments (20)
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