March 19, 2006
Tokers Get Dumber With Every Joint

He's a toker, he's a smoker, he's a fried out joker.

Memory, speed of thinking and other cognitive abilities get worse over time with marijuana use, according to a new study published in the March 14, 2006, issue of Neurology, the scientific journal of the American Academy of Neurology.

The study found that frequent marijuana users performed worse than non-users on tests of cognitive abilities, including divided attention (ability to pay attention to more than one stimulus at a time) and verbal fluency (number of words generated within a time limit). Those who had used marijuana for 10 years or more had more problems with their thinking abilities than those who had used marijuana for five to 10 years. All of the marijuana users were heavy users, which was defined as smoking four or more joints per week.

"We found that the longer people used marijuana, the more deterioration they had in these cognitive abilities, especially in the ability to learn and remember new information," said study author Lambros Messinis, PhD, of the Department of Neurology of the University Hospital of Patras in Patras, Greece. "In several areas, their abilities were significant enough to be considered impaired, with more impairment in the longer-term users than the shorter-term users."

The study involved people ages 17 to 49 taking part in a drug abuse treatment program in Athens, Greece. There were 20 long-term users, 20 shorter-term users and 24 control subjects who had used marijuana at least once in their lives but not more than 20 times and not in the past two years. Those who had used any other class of drugs, such as cocaine or stimulants, during the past year or for more than three months throughout their lives were not included in the study. Before the tests were performed, all participants had to abstain from marijuana for at least 24 hours.

The marijuana users performed worse in several cognitive domains, including delayed recall, recognition and executive functions of the brain. For example, on a test measuring the ability to make decisions, long-term users had 70 percent impaired performance, compared to 55 percent impaired performance for shorter-term users and 8 percent impaired performance for non-users.In a test where participants needed to remember a list of words that had been read to them earlier, the non-users remembered an average of 12 out of 15 words, the shorter-term users remembered an average of nine words and the long-term users remembered an average of seven words.

A longitudinal study would be a lot more convincing. Follow the same tokers for a few years and measure their mental deterioration. Maybe (not that I think this likely) chronic stoners are space cadets even before they become chronic stoners. Or maybe chronic stoners are dumber on average and smarter people decide that getting stoned all the time is just not worth it.

Yeah, maybe. But I doubt it. Heavy duty (multiple times every day) stoner college roommates (not that I ever witnessed criminal activity - this is all hearsay rumours as told to me by other roommates who saw all this while I was at the library of course) whose memories were not first rate came across to me as people who used to be smarter than they were when I knew them. They knew too much about past events and seemed like they once were a lot more together. As kids I figure they didn't used to say "oh wow, I'm supposed to be in class" or "oh wow, I was supposed to meet Lisa for lunch and I like totally spaced". No, I bet they were once a lot more attentive and mentally competent.

If only mainstream left-liberal social scientists hadn't felt the ideological need to collectively decide that the field of psychometrics is the work of Satan some of them would use IQ tests in longitudinal studies of various sorts of drug abusers and we could find out how much damage each recreational drug does to brains.

What practical information I really want to know: Will use of modafinal (Provigil) exact a toll in terms of faster brain aging? Which classes of cognitive-enhancing neuroceuticals won't exact a toll in increased neuronal wear and tear?

Share |      Randall Parker, 2006 March 19 05:58 PM  Brain Addiction

Kip Werking said at March 20, 2006 8:37 PM:

Does alcohol have a similar effect?

Kurt said at March 21, 2006 2:53 AM:

I smoked pot for a very brief period while in high school (about 8 months) and then quit because I no longer enjoyed it. I have always believed that pot causes brain damage in the form of short-term memory loss because everyone I have ever met who smoked pot for an extended period of time was completely spacey and forgetful. Often, they were so forgetful that it could be quite irritating to do anything with them.

Even though I believe in the decriminalization of pot (for civil liberties reasons), Steve Sailor has come up with a very convincing argument for keeping pot illegal. His argument is that pot smoking destroys motivation in young people, many of whom already have problems getting motivated to do anything.

Brett Bellmore said at March 21, 2006 3:48 AM:

But given the "marching morons" phenomenon, where the poor and stupid tend to have more children than the wealthy and smart, isn't it important for our long term genetic heritige to cause brain damage to as many genetically gifted individuals as possible before their prime reproductive years?

Randall Parker said at March 21, 2006 6:25 AM:

Brett Bellmore,

That is a brilliant observation. So what if it damages the brains of smarties if it also causes them to make more genetically smarter babies. So we want the Ivy League students to get stoned every day. Ditto CalTech and MIT students.

A few problems:

- How to prevent those of average and below average intelligence to not get stoned?

- What if the smart stoners are too lazy and lack interest in sex as a result? Plus, what if they get abortions because they feel too lazy to raise kids?

- The economy would suffer as our shrinking group of smart people become both dumber and lazier. We need them to work and make lots of babies.

James Bowery said at March 21, 2006 7:50 AM:

Well, it has to go one of two ways. The way my brother used to put it:

There are 3 kinds of ducks:

1) The dumb ducks fly south for the winter because its time to fly south for the winter.

2) The smart ducks see no reason to follow this atavistic urge to fly south for the winter when you can hang out with other smart ducks and quack at each other about how dumb the dumb ducks are and how smart and disciplined the smart ducks are.

3) The really smart ducks realize they'll freeze their asses off if they don't appear to be dumb ducks to the smart ducks.

It is clear the Ivy League and most of the managerial elite are made up of smart people. Perhaps a drug to simulate the neurotrophic effects of pregnancy:

would help the female ivy leagers to advance to the point that they are really smart.

However, failing that, it does appear it would be better to cause brain damage to smart children, prior to going to any Ivy League school, so they can get a house and a backhoe with which to make a living and raise some smart children, which will, of course, have to be similarly brain damaged so they -- too -- can reproduce.

There appears to be no hope that Ivy League schools will impose a requirement on their students a class in the biological hazard of being smart people.

DaDum said at March 21, 2006 9:08 AM:

As a 30 yr plus smoker I can tell you (and back it up that I think faster than most of the straight people around me). That memory thing; I'm the trivia queen.

If your IQ is below 125 you have no business doing any drugs because you can't afford to lose a point, after that, the more points you lose, the less stupid people you feel like retiring from the world.

I used to take a psych class first thing (8am), stoned off my ass and do memory tests fo the teacher. I was the only one who could recall an hour later what had been written on the board when we walked in, she loved to test me and she didn't even know. I could be brilliant without out it, but have never seen the point.

The hardest test of my life I was so sick I left at lunch, came back slightly bleary eyed and was one of 7 out of 60 who passed the whole test. That scared me. Wouldn't let those people give me directions across the street.

To each his own. Most people have problems figuring out what to eat for dinner, I've planned, shopped, chopped, prepared and presented by the time they usually make up their minds.

You have to have an IQ in order to fully enjoy the perks.

Jim said at March 21, 2006 9:57 AM:

there may be a trade-off between short-term memory and creativity that smoking pot allows one to access.

many people that smoke are more pre-disposed to emotional problems and smoking is a form of self-medication.

hamerhokie said at March 21, 2006 11:29 AM:

I would say that the definition of 'abuse' as applied to marijuana may be substantially different than as applied to alcohol. I drink occasionally, and by that I mean maybe once a month. There is no reason to believe that legalized ganja wouldn't generate a large class of occasional smokers who light up equally infrequently. But I would also guess that as you increase the frequency of use, problems crop up quicker with ganja than with alcohol. Medical studies show benefits of drinking 2-3 glasses of wine per day - no way ganja gets that kind of positive press in any study.

So in the context of decriminalization we have to better define what would be considered 'acceptable use' of ganja, that is, social use with no greater impact to society than our current network of drinking establishments and carryouts impart. My guess is that it would be a great deal less than alcohol, say no more than 2-3 joints per weekend.

Sheila said at March 21, 2006 2:26 PM:

It probably affects different people in different ways. Smartest guy I ever met is now almost a drooling idiot after 30 years of pot and booze. It's been an amazing and appalling thing to witness. But I wouldn't rule out that there are people who can smoke pot regularly and still hang on to their smarts.

gcochran said at March 21, 2006 6:00 PM:

I am reminded of the time my College Bowl team played another team, named the Carbondale Bongs. We were ahead 350 to 0 at the half.

Daniel said at March 21, 2006 7:36 PM:

24 hours abstinance? That isn't enough time to conduct a proper study!!!! The half-life of marijuana is MUCH longer than that. Where do people get off doing studies like these? The longer-term users probably have more tolerance in which case they probably have more THC in their system to get rid of also! Also note that the combination of ALCOHOL with marijuana (which is pretty common) could be a tremendous cause of the cognitive issues that are discussed.

Carbondale Bonger said at March 21, 2006 11:33 PM:

... but once we had the coccaine break at half time, we won 500-350.

I once read a study summary that stated short term memory loss gets a bit worse after 10 beers per week and much more significantly after 25 per week.

Yet recent studies also show amazing brain repair, especially if under 40, for those who sharply curtail or stop drinking. Neurological tests seemed to show no differences if under 40 and not drinking compared to same aged non drinkers.

It would be interesting to see a study tha compared the same groups when none had smoked a joint in 6 months.

Nancy Lebovitz said at March 22, 2006 6:24 AM:

The study was of people at a drug abuse center. It's possible that they'd be more likely to be worried about the effects of pot on their life than the general population of pot users.

As for making it impossible for people to enjoy psychoactives, that's likely to be the way research goes, but maybe it would be saner to look at making it possible to enjoy psychoactives without getting addicted.

Lono said at March 22, 2006 8:26 AM:


I am sorry, but I find these Marijauna "studies" to usually be heavily biased and scientifically flawed.

I think it is safe to say that excess substance abuse has negative effects on the brain - it's a given.

The amount of money spent to specifically demonize "pot" imho shows just how innocuous the drug really is.

Many of my "pot head" friends from college are now professors and top government officials.

Clearly trying to discuss this controvertial topic in absolutes in rediculous - as we all know stoners who have excelled in their various fields.

And we all know promising students who simply dropped out of productive society as well.

However - one thing none of these Marijauna studies ever seem to take into account - is that "pot" can now be effectively and efficently smoked using a vaporizer, which removes many of the toxins from the drug absorbtion process.

How much of an effect these toxins, that can now be easily avoided, contribute to cognitive design will never be properly addressed - because their is no partisan money to fund such a study.

And I myself can attest that psychedelics. properly used, can in fact help increase and augment creative thinking.

Of course - due to the Govt.'s carefully engineered hysteria - I have, and will, avoid further drug use until the laws concerning them can be reformed in the U.S.

gcochran said at March 22, 2006 11:12 AM:

Actually, we won 550-50. We took pity on them, although not a lot.

Nobody said at March 22, 2006 12:45 PM:

As some have pointed out, this study was carried out on subjects of a drug abuse center, and possibly by researchers with an prohibitionist ax to grind, or possibly on subjects with an ax to grind. Expectation and belief of subjects can effect performance in psychological tests.

As another pointed out, the study did not account for any alcohol use during the lifetime consumption pattern.

As yet another pointed out, the abstinence period was only 24 hours, although it is common knowledge that the clearance time for metabolites is on the order of several days.

As Randall pointed out, a longitudinal study would revel a baseline performance capacity which would more clearly reveal the nature of any deficit from long term use.

It is also worth asking what a similar study of alcohol users would reveal. My guess is that with similar frequencies and dosages (dosage defined as a user's preferred dose), an alcohol-only group would test as blithering idiots.

Oddly enough, approximately contemporaneously with the press release reported here, NORML reported another study, in Utrecht, flatly contradicting this one. It is worth noting that the abstinence time in the Utrecht study was much more reasonable.

Here's the URL for the study NORML is reporting:

Frequent Cannabis Use Not Associated With Cognitive Declines In Working Memory, Selective Attention

March 9, 2006 - Utrecht, Netherlands

Utrecht, the Netherlands: Frequent cannabis use is not associated with cognitive deficits in memory or attention, according to trial data published in the forthcoming issue of the journal Psychopharmacology.

Investigators at the Rudolf Magnus Institute of Neuroscience assessed brain function in "frequent but relatively moderate" cannabis users in the domains of working memory and selective attention using functional magnetic resonance imagining (fMRI).

aaaaaaaaaaa said at March 22, 2006 4:11 PM:

Lono writes:
[However - one thing none of these Marijauna studies ever seem to take into account - is that "pot" can now be effectively and efficently smoked using a vaporizer, which removes many of the toxins from the drug absorbtion process.]

This is important, because people hold in hits from marijuana and most tobacco smokers don't inhale at all. Totally ignoring the effect of the THC, a heavy marijuana smoker probably thus causes far, far more damage than a heavy ciggarete smoker. But if it was proven that plant smoke, and not the THC is the cause of most the damage, would the government ever recommend using a vaporizer, or eating it? LOL!

Also, what if people that stay high all the time don't take care of thier health/nutrition as good, thus causing faster permanent cognitive decline indirectly? Or pot smokers just had lower IQ in the first place, causing faster cognitive decline with time due to not being smart enought to take care of health/nutrition.

Also, what if people that stay high all the time don't exercise thier brain as much, causing a "natural" atrophing of brain function (use it or lose it).

Also, I would like to see a study of people that don't drink at all but smoke. That's great that other drug use was eliminated from the study, but why did they ignore alcohol? Did they? Am I wrong? I'ts not far fetched to believe there might have been differential alcohol use among the three test groups.

Also even *if* casual marijuana use is worse on permanent cognitive damage than casual alcohol use (something that seems reasonable, at least for ethnic groups with a long history of alcohol use), *I would still never believe in a million years that marijuana binging is worse than alcohol binging* (even long, long before the point of alcohol poisoning). This is very important for people that like to get trashed. Maybe they should definately stop that and get trashed on marijuana instead. Maybe very vulnerable ethnic groups like native americans should be encouraged to never try alcohol and smoke marijuana instead. They'd probably get the biggest boost from the lesser cognitive damage of alcohol binging vs marijuana binging.

Ken said at March 22, 2006 7:58 PM:

Any studies to say if the alleged loss of capabilities is permanent or if the smoker who quits will regain all that cranial capacity?
as for the habit forming aspect, rarely have any of the studies or doco's I've encountered mentioned the mixing of cannibis and tobacco - most of the heavy pot smokers I've known smoke a mixture, and of course the cravings for tobacco ( occurring under an hour after last use) contribute to making recreational use into habitual use. Presumably the detrimental effects are compounded by the increased frequency of use that can be attributed to the tobacco.

Tom Wright said at March 23, 2006 6:20 AM:

Utterly worthless study. Tiny sample, and more important, self-selected groups. Reminds me of the one that followed teenagers and concluded that users were more likely to experience psychotic episodes. That one ignored the possibility that the teens seeking pot were self-medicating, and the inverse conclusion was more valid--that teens likely to experience future psychotic episodes like smoking pot.
My personal experience (lots) and that of friends tells me that the risks of pot are lower than those for aspirin (assuming oral use.) The drug has essentially no toxic dose. How many drugs can say that?

Football fanatic said at March 23, 2006 10:58 AM:

It seems like I could have told you the same things this study did. My friends that smoked pot in the past are ALWAYS the slowest to speak, slowest to get jokes, and in general, I have met a lot of people who I knew had smoked pot for a long period of time in their past simply because of the way they respond slowly to things.

John Barleycorn said at September 6, 2006 10:06 AM:

It seems like I could have told you the same things this study did. My friends that smoked pot in the past are ALWAYS the slowest to speak, slowest to get jokes, and in general, I have met a lot of people who I knew had smoked pot for a long period of time in their past simply because of the way they respond slowly to things.

Posted by Football fanatic at March 23, 2006 10:58 AM

I smell bullshit, Jock Boy. I have met alot of very intelligent pot smokers, you saying that 'Pot Smokers are the SLOWEST to respond & get jokes' is hilarious. That has got to go down in history as the most uneducated observation ever. I assume they were all stoned when you came to your budget-college hypothesis, and drinking a few cases of Bud too.ose

My pot smoking buddies fall into two groups. Those who smoke (every day, ALOT) and those who occasionally take a hit, and they're good. You're putting them all into the same group as the chronic smokers, which is so obsurd. Even friends of mine who are chronic smokers still hold down good jobs, and are not 'slow' by any means. Live in California for a while my friend, both my Parents smoke pot and are in their 50's. There have been NO long term health effects, my father is a contractor and works his arse off every day ; sometimes while stoned, you'd never know it though. He doesn't get red eyes, he doesn't get the 'munchies' and I'll tell you what if you walked past my parents on the street
you would never, ever, even remotely suspect they were pot smokers. But they are. And they are good people, not 'SLOW'.


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