November 26, 2006
How Marijuana Disrupts Memory Formation In Rats

The reason why your stoner friends can't remember all too well begins to become clear by looking at the effects that marijuana compound tetrahydrocannabinoid (THC) has on the brains of rats.

Neuroscientist David Robbe of Rutgers University and his colleagues tested the impact of THC and a synthetic cannabinoid on rats that had their heads restrained. The drugs affected certain brain waves: the theta (four to 12 hertz) and fast ripple (100 to 200 hertz) waves diminished significantly, whereas the drug had a slightly lesser impact on gamma (30 to 80 hertz) waves. Because theta and gamma oscillations are thought to play a critical role in creating and storing short-term memories--and fast ripple oscillations may allow such short-term memories to be moved into long-term storage--this suppression could mean missing memories for the rats.

The stoners ought to try to remember the details of this research to think about it next time they take a toke.

The THC caused hippocampus nerve signal firings to fall out of sync and to fire less powerfully. The rats had been trained to alternate their routes through a maze and the rats on THC did a far worse job of remembering which route to take next based on which route they took previously.

Normal rats accurately alternate their routes about 90% of the time. But rats given THC, which caused asynchronous nerve firing, chose a random direction on each run, and so chose the correct route 50% of the time.

The disruptive effect of THC wore off within a few hours. Robbe says he hopes to find out whether chronic exposure to the drug causes lasting effects on the hippocampus in rats. Scientists studying people have found that long-term marijuana users gradually become worse at learning and remembering things (see Pot-smoking your way to memory loss).

Neurons that spend a lot of time firing in some different way in response to a drug probably reconfigure somehow in response to the different pattern of firing. Brains strengthen and weaken connections in response to stimuli, whether those stimuli come from the environment or from drugs or an interaction of the two.

What I'd like to know: What does the THC do to change the development of a fetal hippocampus?

Share |      Randall Parker, 2006 November 26 02:49 PM  Brain Addiction


Comments
Omer K said at November 27, 2006 2:38 AM:

Given what even simple amino acids like aspartate and glutamate can do to the hippocampus (which is an area of the brain exempt from the blood brain barrier) as documented in Excitotoxins: The Taste that kills by Russell L Blaylock...

I have to wonder if THC is destroying that area of the brain.

GeneThug said at November 27, 2006 8:42 AM:

As usual, a fascinating post. This makes me wonder if people couldn't use biofeedback to exercise/retrain their thetas to fire harder.

Lono said at November 27, 2006 9:19 AM:

Although these studies are useful - I really fail to see the social implications.

Are we surprised that learning is affected when an animal is intoxicated (or its mental state altered)?

I would argue that memory formation and learning is likely even more disrupted when one is intoxicated with alcohol.

(and I have dealt with both cronic stoners AND cronic alcoholics first hand - and the alcholoics make the stoners seem like brain surgeons - in fact the alcholoics are neraly delusional due to brain damage)

So we can look at a study like this - and state the obvious - kids shouldn't use drugs and cronic stoners need to sober up - but the actual social impact has a much smaller footprint with "dope" than with alcohol.

And when viewed in light of the bigger picture (i.e. the medicinal value of an extremely easy to cultivate herbal remedy) - then studies like these seem somewhat bias as there will likely be no comparrison to other commonly used intoxicants.

But lets continue to push the anti-illegal drug studies here on FP - your not going to convert the knowledgable and for the most part are preaching to the choir anyways.

One day reasonable drug policy is going to replace the corrupt and un-winable "war on drugs" - but until then there will be no shortage of scientists willing to whore themselves out for a piece of the propoganda "pork" pie so that they can pick up a new PS3 for the kiddos.

And Future Pundit will always be there to help them do it!

Omer K said at November 27, 2006 12:47 PM:

Lono,
If your entire point was "Alcohol is worse than marijuana". Id bet half the posters and readers would agree with you.

Dezakin said at November 27, 2006 1:52 PM:

The point is that most of these studies are a waste of time and money to prove the very obvious: Inebriation makes for poor performance.

What they're very good at is being cited by politicians for prohibition policy; If history has been any guide its that prohibition policy is a much greater social failure than dealing with the liberty to indulge in self-destructive behavior.

Lono said at November 27, 2006 2:31 PM:

Dezakin,

Exactly!

(thank you for nicely summarizing my rant ;-)

emerson999 said at November 27, 2006 5:05 PM:

I came in here to throw down some points, which I see have already been addressed by Dezakin, and Lono. The intro, "The reason why your stoner friends can't remember all too well begins to become clear" is in fairly direct conflict with "The disruptive effect of THC wore off within a few hours." I don't use marijuana, and never have. But even so, these kinds of stories always annoy me, just as someone with an interest in how the brain works. The mechanisms by which the drug degrades performance, interesting. Starting with a conclusion based on what you hope a study finds, then twisting a story to fit that preconceived idea, annoying.

I find culture and differing ways societies put value on science to be very interesting. But, science and cultural interpretations of the results are two very different things. And, it's true that one of the most fun things about futurepundit is the aspect of speculation on how technology and new scientific findings will affect society. But it only works when it's in that direction. Science modifying culture, rather than culture modifying the results of science.

Randall Parker said at November 27, 2006 6:01 PM:

emerson999,

I was going for a bit of levity.

I had roommates in college who were stoned most of the time for months and years on end. They also had bad memories. I'm sure others have had such heavy marijuana using friends and roommates and can relate to my comment. But legalizers get all defensive at any evidence for the harm of pot even though Cheech and Chong made a career out of making fun of the memory and other effects of pot.

Dezakin,

These studies are not a waste of time or money. The mechanisms of harmful action of recreational drugs are important to figure out for a few reasons including development of treatments to prevent damage, treatments to reverse damage, and treatments to help people quit. Also, people who are told by marijuana enthusiasts that the risks are slight would benefit from more objective scientific evidence. Would you prefer they made their decisions in relative ignorance? Appparently.

Lono,

I think the harmful effects of recreational and addictive drugs are far greater than legalizers believe. I do not see signs that the legalization advocates have studied the evidence from neurobiology, developmental biology, and other fields. So I created the Brain Addiction category archive to gradually build up a subset (I do not have enough time to follow this more closely) of reports of effects as they get published. Every time I do a post the legalizers get irate and insulting. I figure I'm on to something.

Jake said at November 27, 2006 10:50 PM:

Marijuana can be used for good...even greatness. Despite some inevitable bads...and inevitable bad people.

Your experience depends on who you are, not just with marijuana, with anything.

- Jake.

Rob said at November 28, 2006 7:32 AM:

Randall,
Interesting site, clicked through from a Derbyshire post for my first visit here. Being both a "legalizer" and stoner lemme see if I can clue you in on why the anger creeps up after a post like this. First, I do agree with you somewhat. There is a (I think) healthy defense mechanism that is triggered very easily in legalizers anytime they are confronted with evidence that runs contrary to their personal beliefs that effects of drugs are not nearly as bad (and in some cases the positives outweigh the negatives) as they have been told by the establishment over the course of their lives. Too many lies have been passed as fact by supposedly honest, and trustworthy government officials and organizations that the natural reaction starts to become a rejection of anything that would bolster the opposing sides argument. Most of the time it is warranted, because most of the debates with the "other side" involve liars and crooks, however, it can be provoked in cases where it is not. That is where I would break from you and suggest that you are not "on to something" just because folks get testy when you point to studies that are helpful in making the point that you wish to make. It is nothing more than people who are invested in a long-term debate, who are used to opponents that use every underhanded tactic possible.

My interest in legalization is purely a philosophical and policy matter; while I pay attention to the science surrounding the issue it is hardly my first concern. However, I can accept that bad things can happen to your brain from using drugs, I just think people should be able to choose for themselves if they want to accept that risk. I would also point out that while memory loss shouldn't be shrugged off (and I'm guessing that could suggest other problems could develop over time that are more serious than forgetting where you left your keys) that is hardly a reason to wage a war on a substance. I would also add that studies are constantly released that point to possible benefits of marijuana, prevention of Alzheimer’s being a recent and highly publicized example.

Didn’t mean to get off on a rant and I enjoy reading your stuff.

Cognitive Dissonance said at November 28, 2006 8:07 AM:

"I think the harmful effects of recreational and addictive drugs are far greater than legalizers believe. I do not see signs that the legalization advocates have studied the evidence from neurobiology, developmental biology, and other fields."

I don't see any signs that status quo ante advocates have studied the evidence from the law, sociology, and political science. The period of U.S. history from 1920 to 1933 seems to have escaped their purview as well.

Let me help - the harmful effects of recreational and addictive drugs are far, far outweighed by the cost to society incurred by the drug war. If you'd like to debate the drug war (a matter of law and social policy), go right ahead. But instead you're telling people that drugs can be bad for you. I don't think *anyone* doubts the science that drugs have harmful side effects. It's just not relevant to the discussion of the drug war.

The drug war isn't about neurobiological studies. The drug war isn't the outgrowth of some government policy to keep us safe from things that harm us. The drug war isn't even consistent in its use of science to justify making certain drugs totally illegal and other drugs only partially illegal. The drug war *is* the outgrowth of people who enjoy asserting control over other people's decisions and choices. And ironically enough, the drug war was created by people who misrepresented the available science to an unsuspecting public It is a morally bankrupt war (you scientists may not understand moral bankrupcy, so I'll simply say that it's a bad thing). Its intended and unintended consequences far outweigh any possible benefit to society. Other societies which have tried other solutions, including legalization of marijuana (like the Netherlands) have demonstrably better outcomes. Check out this post from Classical Values on Afghanistan. The drug war, in this case, is preventing companies from buying Afghanistan's poppy crop and using it to produce legal morphine. Instead, the money goes to fund terrorism.

Huzzah! Thanks, drug warriors!

The drug war, like Prohibition before it, is an unmitigated disaster which cannot be rationally defended by any sane individual fully apprised of the social costs and scientific inconsistencies involved. I'm cheering for the 28th Amendment to lift this long national nightmare from our eyes.

The only drug I use is tobacco, so don't try and tar me (pun intended) with some dirty brush you've got there. I'm not in this so I can sit around and get baked. I'm in it so glaucoma patients and their doctors can make their own decisions about the best way to treat their disease, without people like Randall stepping in and telling them to worry more about their minor temporary memory loss than their permanent vision loss and abject utter pain. I'm in it so no one else's 88-year-old grandmother gets murdered in Atlanta on a no-knock police raid. I'm in it so no more homes are broken by self-righteous zealots who'll gladly throw a young father in jail for smoking a joint. This is a socio-political issue, not a scientific one. And moreover, the science happens to be on the side of the physicians - AGAINST the drug war. I'll see you in Washington.

Cogsys said at November 28, 2006 10:41 AM:

Buying Afghan poppy crop seems very reasonable ("Let a Thousand Licensed Poppies Bloom," NYT). "Developing countries are home to 80 percent of the world's population, but they consume just 6 percent of the medical opioids. In those countries, most people with cancer, AIDS and other painful conditions live and die in agony."

The following kind of reactionism tends to discredit otherwise acceptable positions: "without people like Randall stepping in and telling them to worry more about their minor temporary memory loss than their permanent vision loss and abject utter pain."

Randall Parker said at November 28, 2006 7:46 PM:

Rob,

But I do not see drug use as solely a matter of someone deciding what risks they will take with their own body. What about developing embryos on cocaine, heroin, THC, and meth? Are those embryos exercising free will? What are the costs to the rest of us when babies are born premature, on coke, and likely to have lower IQs and ADHD? What are the costs to those babies?

Also, there's some evidence that marijuana increases the risk for schizophrenia in susceptible individuals. Well, who pays when someone becomes a schizophrenic? The rest of us.

Cognitive Dissonance says:

The drug war isn't about neurobiological studies.

It is for me.

Cogsys,

I think dying people should be able to take heroin or morphine or LSD for that matter. The risk/benefit trade-off is completely different for them. I think even addictive and hallucinogenic drugs have valid medical uses. I do not see the point of denying drugs from people who have metastatic cancer.

Nancy Lebovitz said at November 29, 2006 4:04 AM:

Have there been any studies on the neurological effects of being imprisoned? Surely, they should be considered when evaluating the effects of the illegalization of drugs.

Dezakin said at November 29, 2006 4:31 AM:

Also, people who are told by marijuana enthusiasts that the risks are slight would benefit from more objective scientific evidence. Would you prefer they made their decisions in relative ignorance? Appparently.

And the strawman burns. Look, you have your axe to grind, but you could paint up the effects of long term caffine consuption, online games, or watching bad TV with similar studies. Sure you might yield some interesting data, but its prime audience would be policy advocates against the harmful effects of watching an episode of 'Friends.' I can see it now... Study shows World of Warcraft leads to obesity, hypertension, and sleep disorders. Legislation against WoW called for by many.

What all this leads into is FP becoming yet another policy advocacy site.

What about developing embryos on cocaine, heroin, THC, and meth?

What about them? Most people who are pregnant use relatively sound judgement with regards to recreational drugs. These are fringe issues used to justify prohibition, along with the spectre of addicts who turn to crime to feed their habit.

I think dying people should be able to take heroin or morphine or LSD for that matter. The risk/benefit trade-off is completely different for them.

I think the person most prepared to evaluate the risk/benifit tradeoff of me is me.

Rob said at November 29, 2006 9:36 AM:
But I do not see drug use as solely a matter of someone deciding what risks they will take with their own body. What about developing embryos on cocaine, heroin, THC, and meth? Are those embryos exercising free will? What are the costs to the rest of us when babies are born premature, on coke, and likely to have lower IQs and ADHD? What are the costs to those babies?
Humm....By that logic we should legislate what food parents provide for children, because it isn't there choice that Mom likes to fry foods, or to save time and money she picks up pizza or fast food a couple times a week. And obviously alcohol consumption should be made illegal for expectant mothers, right? We should probably just go ahead and expand that to anyone with a child in their home should not be allowed to touch booze because of the potential problems that could arise (drug driving accident, domestic abuse, etc). You see my point? Just because some people will not be responsible for their own lives and that of their children does not mean that we should legislate everyone's behavior. The cost benefit analysis just doesn't work out favorably for that policy. Decisions, and behaviors related to those decisions, can have impact on others but just because that's the case it doesn't mean we should make it our job as a society to attempt to protect everyone. It just isn't realistic, it isn't fair to those who are adults and can act responsible, and in many cases (like our current War on Drugs) it causes much, much more harm than the alternative of allowing people to make their own behavioral choices.

The evidence that THC can lead to schizophrenia in, as you put it, "susceptible individuals" is at best tenuous and at worst a classic example of fear mongering. I can point to a number of studies that show no evidence linking THC with the onset of schizophrenia in any demographic, including a rather extensive one commissioned by the New Zealand parliament in 2003. There isn't hard evidence for either side of the argument, certainly not enough to use it as a reason to throw people in jail for smoking marijuana.

I noticed in a follow up comment by you in this discussion thread, you wrote

I had roommates in college who were stoned most of the time for months and years on end. They also had bad memories. I'm sure others have had such heavy marijuana using friends and roommates and can relate to my comment. But legalizers get all defensive at any evidence for the harm of pot even though Cheech and Chong made a career out of making fun of the memory and other effects of pot.
Ok if we get to use anecdotal evidence in making these arguments let me take some guesses. My guess would be that your roommates were probably easygoing guys, a bit sloppy and rather quiet in their behaviors. Probably never caused you much trouble, or put you in harms way due to their drug use. In my years around smokers that is the typical profile. (fair game to make these assumptions) As a matter of fact I would guess that the greatest risks to you or to them via their smoking were all due to marijuana's illegal status. The risks of dealing with criminals in procuring the marijuana, the risks of incarceration due to possession, the risks of harm from police, the chance you get kicked out of school...etc. Those are the real harms caused by THC and those are not caused by the drug itself, rather from our asinine policies to control usage and possession. Those are harms that the state can actually prevent, so why don't they? Instead they act as a paternalistic nanny-state continuously attempting to assure us that they know what is best for us, even though it flies in the face of what we encounter in our daily lives and what we see in our communities. That in a sentence is what causes the decriminalization movement to react so aggressively to the arguments you/they make.

Sorry for the length.

tpiddy said at November 29, 2006 4:27 PM:

Randall,

you think dying people should be able to use all substances? we are all dying. you could be hit by a car or lightning tomorrow.

society pays for a lot of bad decisions that others make, and is used to it.

Randall Parker said at November 29, 2006 5:15 PM:

tpiddy,

We aren't all suffering chronic pain, weighing half our normal weight, with failing organs, and bones riddled by cancer.

People who are terminal with specific diseases have very different risk/benefit trade-offs.

On what society is used to: Society is very used to criminalizing behaviors that create risks for self and others.

Dezakin,

I'll turn FP into a policy advocacy site by telling legalizers they are unrealistic and ignoring the costs of drug use? How ridiulous. I've spent 20 times more effort or more advocating on energy policy. I've made many posts on biomedical research spending policy. You just do not like my position on this one issue.

Similar studies on other subjects? It depends on what you mean by "similar". I've very curious to know what the longer term effects are of heavy violent video game playing on adolescent brains. I'd certainly post on this if I came across something. But it is harder to study than drugs since drugs can be studied on animal models.

One of my major themes is that we did not evolve to fit in the environment we find ourselves in. Therefore, predictably, we are not designed to properly handle our environment. Many technologies cause us to be maladaptive. Drugs are just one of them.

To evolutionary theorists like Greg Cochran this argument is obvious. To libertarians it is deeply offensive.

As for pregnant women and use of alcohol, cigarettes, and drugs: This is a huge problem. Legalizers are denying reality when they deny the problem is big.

Meth use among pregnant women is a large and growing problem:

Because crystal meth is relatively easy to make and buy - it can be cooked up in home laboratories with accessible ingredients and bought for $5 to $10 a hit - global use of the drug is skyrocketing, especially among young women, the researchers say. While national statistics for Canada are not readily available - figures vary from province to province - an estimated 500,000 Americans are believed to be regular users, including five per cent that are pregnant women.

The study, published online ahead of print in the fetal and neonatal edition of the Archives of Disease in Childhood, involved tests on hair samples from 8,000 mothers and newborns from across Canada that were sent to the Motherisk Laboratory for analysis between 1997 and 2005.

Almost 400 of the samples sent by doctors or children's aid societies tested positive for meth, including 11 mother and baby pairs. The first positive cases - six in all - were found in 2003. The next year, eight hair samples contained evidence of methamphetamine use. But in 2005, the number soared to more than 300.

"It's a looming epidemic, it's like a big black cloud," said Koren. "For sure we know that a significant group of Canadian kids have addicted mothers."

Cognitive Dissonance said at November 30, 2006 6:55 AM:

"I'll turn FP into a policy advocacy site by telling legalizers they are unrealistic and ignoring the costs of drug use? How ridiulous. . . . As for pregnant women and use of alcohol, cigarettes, and drugs: This is a huge problem. Legalizers are denying reality when they deny the problem is big."

Your study merely shows that some dude is using scary language to get his name and his study in the mainstream news. While I realize that crack babies are not meth babies, I will note that the University of Florida has found:

“In all of the various outcomes we have looked at, people have expected very bad things,” said Tamara D. Warner, a postdoctoral associate in the UF College of Medicine and lead author of the study. “These dire predictions were made about this group of kids. This study shows there really aren’t the huge problems that we might expect.”
Article here: Prenatal cocaine exposure not linked to bad behavior in kids.

"On what society is used to: Society is very used to criminalizing behaviors that create risks for self and others."

Society is used to criminalizing behaviors that create risks for self? What, like laws against onanism? Laws like those overturned by the Lawrence v. Texas decision? Laws like those overturned by the 21st Amendment? Or are you aiming more squarely at laws like those overturned by the Roe v. Wade decision? Can you clarify which laws you speak of?

I'm interested to hear more from you about why the drug war isn't about social policy and law, but rather about neurobiology.

Dezakin said at November 30, 2006 12:35 PM:
I've spent 20 times more effort or more advocating on energy policy. I've made many posts on biomedical research spending policy. You just do not like my position on this one issue.
I haven't liked your position on other issues, but this issue isn't about banal issues science or spending policy. Its about the role of the state versus the individual. Its pure politics, and the positions are tied up more in philosophical outlook on the role of the state than anything else. Some are comfortable with the state making arbitrary decisions about personal behavior that may or may not have negative externalities, and others aren't. Oh we could then delve into economic studies of which is most costly, prohibition or decriminalization or full legalization, but its all fuel for the fire for a shouting match.
As for pregnant women and use of alcohol, cigarettes, and drugs: This is a huge problem. Legalizers are denying reality when they deny the problem is big.

Right. Consumption of alchohol is a during pregnancy is a recent phenomenon having untold tragic effects on society.

Next on FP: People healthier and happier in the police state. Big brother really does know whats best for you.

Kurt9 said at November 30, 2006 1:39 PM:

I think the fact that marijuana use damages short-term memory is obvious to anyone who has had friends who smoke alot of pot. One of my best friends in high school smoke pot consistantly from age 15 until his late 20's. When we were 17 or so, he was so absent mindedly forgetful that it was actually quite irritating to do anything with him or expect him to remember anything (like bringing notes to a meeting). I had another friend in SoCal (late 80's) who used to be a real hippie (attended Berkeley in the late 60's) and did a lot of the hallucinogens (pot, shrooms, LSD, etc.) over a 10 year period. By the time I met him, he had long since quit drugs and was actually quite anti-drug. He was forgetful as hell and was also quite irritating to deal with as well.

I've believed since high school (1981) that pot damages short term memory and that it is actually worse for you than its pundits claim. Steve Sailor argues that pot is bad because it make people lazy. I think this is relevant as well. Why do we need more lazy people around than we have already?

The issue of prohibition is more complicated. Even though I think all of these "recreational" drugs are bad for you. I am not necessarly in favor of prohibition. I think that the war on drugs has cost us some of our liberties (not to mention the policy raids that are quite commonplace these day).

Like you, Randall, I agree that research into the actual molecular biological effect of these substances is useful for clarifying the pertinent issues with regards to legalization vs. criminalization.

The legalizers have a point with regards to your average job blow taking these things. However, they fail to account for the fact that you have pregnant women taking these drugs and the resulting babies with medical conditions that result from this.

I do agree with the legalizers that the original motivation for drug prohibition was not primarly about neurobiology. However, neurobiology is an important part of the debate about decriminalization.

Randall Parker said at November 30, 2006 7:40 PM:

Cognitive Dissonance misleadingly states:

I'm interested to hear more from you about why the drug war isn't about social policy and law, but rather about neurobiology.

Let me connect the dots which you've disconnected: I think policy and law should be shaped using knowledge from science. I do not think policy should be made purely from philosophical beliefs some people hold about the proper role of the state.

People embrace ideologies (e.g. communism, liberalism, libertarianism) as secular faiths. The secular faiths are no more rational than the religious faiths. They are more prone to disproof, however, because they hold beliefs about this world. I do not put libertarian tenets or my own personal preferences for how I'd ideally like to see a society governed ahead of what the evidence points me to. But I see others bucking against the evidence every day.

In answer to your question: "Society is used to criminalizing behaviors that create risks for self?": Yes, suicide is against the law. So is driving a motorcycle without a helmet. The consensus seems to be that people do not have a right to turn themselves into vegetables that have to be taken care of in state-funded homes. Or to leave their kids destitute.

As for crack babies versus meth babies: Cocaine causes placental vascular constriction. More of the evidence is available in animal models because more can be done with them obviously. See, for instance, this 2002 paper Developmental toxicity of cocaine exposure in mid-pregnancy mice. Also see this other 2002 report: Using Cocaine During Pregnancy May Damage Developing Fetuses, Causing Lifelong Learning Disabilities. For a human study see also from 2002 At 2 years, cocaine babies suffer cognitive development effects.

What is tragic about the effects of cocaine is the punishment in the form of depression that addicts feel and the drug kills of dopamine neurons making this depression deeper.

The researchers examined brain samples removed during autopsies of 35 known cocaine abusers and 35 non-drug users chosen for similar age, sex, race or cause of death. They used three standard molecular measurements to evaluate the condition of dopamine brain cells. They found levels for all three standards were significantly lower for cocaine users than for the control subjects. The levels were lowest among cocaine users who had been diagnosed with depression.

"About a third of cocaine users feel markedly depressed, listless, anxious, and uncomfortable when they stop using cocaine, and this persists in a sizeable number," Little said.

Little, who also is chief of the VAHS Affective Neuropharmacology Laboratory in Ann Arbor, said, "We know that people who have those symptoms are likely to become more dependent on the drug and find it harder to quit. So, cocaine is most addicting to those individuals who experience not only pleasure from its use, but are also punished by its withdrawal. Our results provide a very good biochemical basis for cocaine withdrawal symptoms."

Neurotoxic effects of fetal nicotine exposure may predispose adolescents to become more easily addicted to nicotine as well:

Offspring of women who smoke during pregnancy are themselves more likely to take up smoking in adolescence. We evaluated neurotoxicant effects of prenatal and adolescent nicotine exposure in developing rats to evaluate whether these contribute to a biological basis for this relationship. Rats were given nicotine or vehicle throughout pregnancy and the offspring then again received nicotine or vehicle during adolescence (postnatal days PN30-47.5); this regimen reproduces the plasma nicotine levels found in smokers. Indices of neural cell number (DNA concentration and content), cell size (protein/DNA ratio), and cell membrane surface area (membrane/total protein) were then evaluated in brain regions during adolescent nicotine administration (PN45) and up to 1 month post-treatment. By itself, prenatal nicotine administration produced cellular alterations that persisted into adolescence, characterized by net cell losses in the midbrain and to a lesser extent, in the cerebral cortex, with corresponding elevations in the membrane/total protein ratio. The hippocampus showed a unique response, with increased DNA content and regional enlargement. Adolescent nicotine treatment alone had similar, albeit smaller effects, but also showed sex-dependence, with effects on protein biomarkers preferential to females. When animals exposed to nicotine prenatally were then given nicotine in adolescence, the net outcome was worsened, largely representing summation of the two individual effects. Our results indicate that prenatal nicotine exposure alters parameters of cell development lasting into adolescence, where the effects add to those elicited directly by adolescent nicotine; neurotoxicant actions may thus contribute to the association between maternal smoking and subsequent smoking in the offspring.

Cocaine is a neurotoxin. So is methamphetamine. So is nicotine.

In 2002 Yale researchers found evidence that coke exposure in pregnancy might cause ADHD.

New Haven, Conn. Taking cocaine during pregnancy causes possibly permanent changes in an area of the brain that governs short term memory leading to symptoms that are very much like attention deficit hyperactivity disorder, Yale researchers have found in two recent studies.

The research team in the Neuropsychopharmacology Laboratory at Yale School of Medicine found that prenatal exposure to cocaine leads to over-stimulation of the medical prefrontal cortex of the brain in the offspring, and a dramatic impairment in learning.

"Children exposed to cocaine in the womb may have a problem with excitable neurons in part of the brain that helps control attention and memory," said Bret Morrow, associate research scientist, associate clinical professor and lead author of both studies. "Potentially, this excitable prefrontal cortex may be the basis of the learning deficits in these children."

"The use of cocaine among women of childbearing age is alarmingly high," he added. "When a pregnant woman uses cocaine she also exposes her fetus to the drug. Studies have shown that these cocaine exposed children have increased occurrence of symptoms similar to those seen with attention deficit hyperactivity disorder increased distractibility, impulsivity and select learning deficits. Based on our animal studies, we are concerned the effects could very well be lifelong in humans."

Many abused drugs cause increasingly well characterised patterns of neural damage.

There is increasing evidence that the fasciculus retroflexus (FR) represents a 'weak link' following the continuous administration of drugs of abuse. A variety of drugs which predominantly potentiate dopamine, including D-amphetamine, methamphetamine, MDMA, cocaine, and cathinone, all induce degeneration in axons from lateral habenula, through the sheath of FR, to midbrain cells such as SN, VTA, and raphe. For some drugs, such as cocaine, this is virtually the only degeneration induced in brain. Continuous nicotine also selectively induces degeneration in FR, but in the other half of the tract, i.e. in axons from medial habenula through the core of the tract to interpeduncular nucleus. This phylogenetically primitive tract carries much of the negative feedback from forebrain back onto midbrain reward cells, and the finding that these descending control pathways are compromised following simulated drug binges has implications for theories of drug addiction but also psychosis in general.

It is hard to do long term controlled studies of kids exposed and not exposed to coke or other drugs, control for all variables, and measure all relevant types of cognitive function. I look at the neurobiology results and figure the social science will evemtually go in the direction that the neurobiology research points: Fetal exposure of most or all of the major abused drugs causes lasting harm.

Lono said at December 1, 2006 7:19 AM:

Randall - you stated:

"Let me connect the dots which you've disconnected: I think policy and law should be shaped using knowledge from science. I do not think policy should be made purely from philosophical beliefs some people hold about the proper role of the state."

Now - as a long time reader of Futurepundit I think you generally do use that approach in your posts, however, when it comes to the topic of illegal drugs I do not believe this is true.

I believe you react more emotionally based on your own negative experiences with illegal drug users.

I think the science clearly and thouroughly supports the notion that Marijuana not only has legitimate (and important) medicinal value, but also that it is much safer for adult use than legal drugs such as nicotine and alcohol (even for pregnant or nursing mothers - although clearly no one approves of that)

So therefore - if you want to put your money where your mouth is - you clearly must favor a decriminalization policy towards marijuana (based on scientific risk analysis) or you must believe in total prohibition of all potentially harmful drugs (including nicotine, alcohol, and even caffine).

You really (by your own admission) shouldn't use specific, out of context, scientific studies to support your philosophical beliefs.

Myself - I don't personally believe scientific knowledge should be the basis for Human social policy - but I do think it is an important element to consider.

I think your stance thus on illegal drugs may have a hint of hypocrisy when examined by an impartial party.

I do, however, believe that knowing the scientific risks and benefits of any substance is of great importance to Humanity - so I thank you for keeping us hear at FP so well informed.

Randall Parker said at December 1, 2006 3:55 PM:

Lono,

I've read a lot more about the neurobiology of illicit drugs than I've ever posted. Remember, I only started writing this blog 4 years ago. I started learning biology in the late 70s.

Studies of the effects of drugs on fetal development of mice and rats aren't out of context. They are highly in context. Humans are genetically close enough to rodents to make rodents great models for figuring out human biology. Brain scan studies and autopsies on human brains to study drug damage are in context as well. Not sure what you think I've posted that is out of context.

My own negative experiences with illegal drug users account for nothing but irrational emotional reactions? It was these people who got me much more scientifically interested in illicit drug use. How much permanent damage are all these people doing to themselves? How irreversible is it? Are they damaging their babies too? Seeing things up close and personal creates lots of questions in my mind. Then I go searching for answers to them. I fail to see how this makes me irrational.

I know just how permanent (absent genetic engineering, stem cell therapies, and nanobots) development wrong-turns are for mammals. I think the legalizers are being cavalier and irresponsible to discount developmental damage from drug exposure.

As for nicotine and alcohol and pregnancy: The argument that we tolerate harmful thing X and therefore we should tolerate harmful thing Y is irrational. That's a prescription for a slippery slope of an ever worsening society. Rather, I think we ought to look for ways to reduce the damage done by both X and Y.

I think pregnant nicotine addicts and pregnant alcoholics should be locked up in care facilities and isolated from their addictions until they give birth. I'm not sure what we should do with smoking moms and dads who have babies. But I'm willing to use the power of the state to prevent people from doing serious lifelong damage to their offspring. We pay for that damage in welfare state support, higher crime, higher car accident rates (with injuries and deaths), and in other ways. Plus, the babies born to these people suffer their own hells as do their parents.

I've seen how stressed and unhappy it makes a mom to deal with an ADHD child in adolescence. The mom I'm thinking of is plausibly afraid her kid is going to kill people on the road because he's so impulsive behind the wheel. Drugs that do development damage to cause ADHD undoubtedly cause injury and death both by car accidents and by violence. Low impulse control translates into more acts of violence.

My take on the laissez faire libertarian approach is that it accepts far too many very damaging rights violations by individuals.

Bob Badour said at December 2, 2006 10:22 AM:

Nancy Lebovitz,

Have there been any studies on the neurological effects of being imprisoned? Surely, they should be considered when evaluating the effects of the illegalization of drugs.

Convicted criminals have had due process and lost some of their rights. Whether incarceration causes convicted criminals any damage is less relevant than the fact that imprisoning convicted criminals protects the rights and freedoms of those who respect the law and the rights of others.

Dezakin,

What about them? Most people who are pregnant use relatively sound judgement with regards to recreational drugs.

Most people who are pregnant are not addicted to recreational drugs in the first place. Most pregnant women who are or have been addicted to recreational drugs use relatively unsound judgement with regards to the welfare of their unborn children. As one of Randall's recent articles pointed out, addiction impairs the ability to weigh relative dangers and rewards.

Rob,

in many cases (like our current War on Drugs) it causes much, much more harm

Please define the harm caused by the war on drugs. Greater incarceration rates have reduced the overall crime rate including the rate of murder. What is the harm in making the streets safer?

Randall Parker said at December 2, 2006 11:31 AM:

Bob,

You are missing the real problem with Dezakin's reference to "Most people who are pregnant": If only 1% of pregnant women abuse drugs that's 1% of future babies born damaged. That's future crime, high school drop-outs, car accidents, low income, more need for welfare benefits, more tendency to abuse others.

The idea that something is okay if most people can handle it is a farce. When it comes to women making babies the cost of harm to fetuses is enormous. The damage is there from birth. The cost is paid throughout the baby's life.

Libertarians focus on the costs of government actions but ignore the costs of individual actions.

Bob Badour said at December 2, 2006 1:07 PM:

Very true--especially when considering the high percentage of crime is committed by the 1% most criminal among us.

Rob said at December 3, 2006 11:31 PM:

Bob,

You got about a month? I might be able to reverse some of the brainwashing you've encountered over the years. No promises please undestand, but I'm hopeful and confident in my abilities.

In all seriousness, I'm not gonna re-ignite this thing with a boring post/comment about the harms done by the Drug War. I'm sure you've heard it all before and don't agree with most of it (You clearly have no problem with throwing as many people in jail as humanly possible.). But on the off chance that you are legitimately asking the question, check out the fantastically low-brow blog tothepeople.com. I focus on the Drug War at that community blog (and post daily on the drugs, current policies, international problems caused by our War on Drugs, etc. Check out other crazy, drug legalizing publications like National Review (search the archived articles, they've got plenty solid commentaries on the War on Drugs), Reason, drugwarant.com...to name a few.

Have fun.


Randall Parker said at December 4, 2006 10:08 PM:

Rob,

The National Review is crazy. It used to be a conservative publication. Emphasis on past tense. The purge in the late 90s ushered in the neocons and Bush sycophants.

Reason? I used to read it. Libertarianism is as flawed as communism because it is based on false assumptions about human nature. It is yet another ideology. All ideologies are simplifications of reality.

Arbormbracer said at May 7, 2007 11:43 AM:

LOL the author of this obviously didn't quite understand the data he supposedly synthesized. My professor was one of the research scientists in this experiment. People seem to think the idea of memory is a lot more general than it actually is. The rats showed signs of GOOD memory loss. Yes, sometimes it is important to forget things in order to create new memories. Watch out for writers who exhibit little to no understanding of the data they relay by offering no explanation of a process and only its conclusion! It also looks like the author of this article stopped after reading one finding of this research and thus the article is inconclusive and irrelevant.

stress said at November 3, 2007 10:39 PM:

ahh, this old argument. Am I the only one here who finds it absolutely hilarious when the no fun police base their verbose rants against pot smokers and loss of memory on, "this guy I went to college with?" Do I think pot smoking causes some memory loss and brief lack of concentration? Definitly. I also PERSONALLY know many brilliant, pasionate, life-loving, healthy and most importantly, GOOD-responsible human beings who smoke daily. I also know sober people who fit snugly into that 1% of top criminals. Oh, if only their mothers weren't smoking reefer and listening to jazz music during pregnency the world would be just like a Disney movie. I don't need an inept government making my lifestyle choices. My lifestyle choices do YOU no harm so study your own imperfections please.

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