No, Marijuana Use Doesn't Lower Your IQ

[The General]

A 2012 Duke University study made international headlines when it purported to find a link between heavy marijuana use and IQ decline among teenagers. Other researchers questioned the findings almost immediately: Columbia University's Carl Hart noted the very small sample of heavy users (38) in the study, leading him to question how generalizable the results were.

Then, a follow-up study published 6 months later in the same journal found that the Duke paper failed to account for a number of confounding factors: "Although it would be too strong to say that the results have been discredited, the methodology is flawed and the causal inference drawn from the results premature," it concluded.

Now, a new study out from the University College of London provides even stronger evidence that the Duke findings were flawed. The study draws on a considerably larger sample of adolescents than the Duke research - 2,612 children born in the Bristol area of the U.K. in 1991 and 1992. Researchers examined children's IQ scores at age 8 and again at age 15, and found "no relationship between cannabis use and lower IQ at age 15," when confounding factors - alcohol use, cigarette use, maternal education, and others - were taken into account. Even heavy marijuana use wasn't associated with IQ.

"In particular alcohol use was found to be strongly associated with IQ decline," the authors write. "No other factors were found to be predictive of IQ change." The UK study does find evidence, however, of slightly impaired educational abilities among the very heaviest marijuana users. This group of students scored roughly 3% lower on school exams taken at age 16, even after adjusting for confounding factors.

In a press release accompanying the study, lead author Claire Mokrysz noted that "this is a potentially important public health message- the belief that cannabis is particularly harmful may detract focus from and awareness of other potentially harmful behaviours." Reviewer Guy Goodwin of Oxford University agreed: "the current focus on the alleged harms of cannabis may be obscuring the fact that its use is often correlated with that of other even more freely available drugs and possibly lifestyle factors. These may be as or more important than cannabis itself."

This is a key point. Many skeptics of legalization in the United States focus on the potential harms of marijuana use alone. But marijuana use is just one of many behaviors that can possibly affect life outcomes. In many cases these other behaviors are likely to play a much larger role in determining a person's trajectory through life.

It also partly explains why even as we've seen increasingly permissive laws regulating marijuana use in the past decade, there has been no corresponding uptick in negative outcomes. It's perfectly reasonable to assume that heavy use of marijuana - or any substance - in your teen years will lead to poor educational performance. Thus for states that are legalizing the drug -- Colorado and Washington so far - it makes sense to limit legal marijuana use to 21-and-over. But this study is the latest in a growing, robust body of evidence suggesting it makes little sense to focus on marijuana use to the exclusion of all other factors.

News Moderator - The General @ 420 MAGAZINE ®
Source: Washingtonpost.com
Author: Christopher Ingraham
Contact: Contact Us
Website: No, marijuana use doesn't lower your IQ - The Washington Post

 

[Mike Wright]

Google hippocampal neurogenesis. Cannabis actually promotes the growth of new brain cells in the hippocampus.

 

[painkills2]

I tend to over-analyze things, so if I were to guess at my IQ score when I was taking prescription medications -- compared to what my IQ was like at the end of my year in the medical cannabis program -- I'd say I'm smarter now. Even if my IQ score hasn't changed at all, I feel smarter.

I feel, therefore I am...

 

[zigzag1949]

I tend to over-analyze things, so if I were to guess at my IQ score when I was taking prescription medications -- compared to what my IQ was like at the end of my year in the medical cannabis program -- I'd say I'm smarter now. Even if my IQ score hasn't changed at all, I feel smarter.

I feel, therefore I am...

I have been a heavy pot smoker since the late 60's. In 1980 I took the test for entrance into Mensa and score 136 and 142 on the 2 test that night. In 2010 I took another IQ test to challenge a friend about whose was higher. I scored 144 now if there was any truth to the myth that it lowers your IQ you would think it would have showed up by now.
Smoke on brothers

BTW my High School transcripts showed an IQ of 110 my 10th grade year go figure.

 

[Ravyn]

except for brief breaks while traveling, I have used cannabis daily since age 15; over 35 years. My IQ tests at 136 now, as it did when I was in high school. there is a difference between IQ and how your grades turn out though. If you skip class to go smoke pot, and then come back with a big grin on your face, in time for a surprise test, you might not do so well.

 

[Radogast]

Riding your grades by skipping class and smoking pot is a natural consequence.

Being given bad grades because those in authority don't like you smoking pot is a vindictive consequence.

Getting dumber by smoking pot? That's a figment of someone's imagination, it doesn't happen!

 

[painkills2]

I don't know what my IQ is, but I question assigning people a number that's supposed to be the measure of their intelligence...

From Wikipedia:

Some scientists dispute IQ entirely. In The Mismeasure of Man (1996), paleontologist Stephen Jay Gould criticized IQ tests and argued that they were used for scientific racism. He argued that g was a mathematical artifact and criticized:

"...the abstraction of intelligence as a single entity, its location within the brain, its quantification as one number for each individual, and the use of these numbers to rank people in a single series of worthiness, invariably to find that oppressed and disadvantaged groups–races, classes, or sexes–are innately inferior and deserve their status."

"Some studies indicate that IQ is unrelated to net worth."

Like my credit score, whatever my IQ is, it doesn't really say that much about me.

 

[Mike Wright]

IQ is a standardized measure of certain specific cognitive capabilities, nothing more. It does not generalize to anything like "intelligence." It does reveal how quickly or effectively one can solve certain types of tasks.

Cognitive science was one of my main hobbies for about 5 years, especially the cybernetics of consciousness. Several administered tests between childhood and young adulthood pegged me steadily between 138 and 142. This score was always heavily weighted by my verbal reasoning component. I am a verbal thinker, visual not so much. My visual thinking component seemed to top out at about 120.

A couple of years ago I became interested in a certain effect called 'hippocampal neurogenesis'. Large daily doses of orally consumed THC cause the growth of new neurons in the brains of mice. I undertook to eat one gram per day regularly for nearly a year. Simultaneously I was reading academic texts as well as doing lots of writing. (Any kind of brain development absolutely requires mental activity as well as mere physical development).

I did take some IQ tests and scored 166 on one. I did notice that I was much more successful on the visual component this time. I could 'feel' that my visual intuitions were just....better.

I think if you consume a lot of cannabis and don't do much on a regular basis you are not going to do your brain any favours, any more than if you just sit around and veg high or not. My wife and I are both very active when we medicate. We do chores, exercise, read, write, play and compose music.

The bottom line is that if you are being creative and constructive both your brain and your thought processes will benefit. IQ is just one subset of mental activities.

 

[Lady Vadalon]

I would like to read the white papers on this one. Some studies can be bias like the Duke paper. And it never stated if it was a blind study test. I hate the word IQ test, what one did they use and for what region?

 

[Lady Vadalon]

IQ is a standardized measure of certain specific cognitive capabilities, nothing more. It does not generalize to anything like "intelligence." It does reveal how quickly or effectively one can solve certain types of tasks.

Cognitive science was one of my main hobbies for about 5 years, especially the cybernetics of consciousness. Several administered tests between childhood and young adulthood pegged me steadily between 138 and 142. This score was always heavily weighted by my verbal reasoning component. I am a verbal thinker, visual not so much. My visual thinking component seemed to top out at about 120.

A couple of years ago I became interested in a certain effect called 'hippocampal neurogenesis'. Large daily doses of orally consumed THC cause the growth of new neurons in the brains of mice. I undertook to eat one gram per day regularly for nearly a year. Simultaneously I was reading academic texts as well as doing lots of writing. (Any kind of brain development absolutely requires mental activity as well as mere physical development).

I did take some IQ tests and scored 166 on one. I did notice that I was much more successful on the visual component this time. I could 'feel' that my visual intuitions were just....better.

I think if you consume a lot of cannabis and don't do much on a regular basis you are not going to do your brain any favours, any more than if you just sit around and veg high or not. My wife and I are both very active when we medicate. We do chores, exercise, read, write, play and compose music.

The bottom line is that if you are being creative and constructive both your brain and your thought processes will benefit. IQ is just one subset of mental activities.

So, you were consuming it and not smoking at all? I agree that if any person using cannabis or not using cannabis and are active and not just laying around the brain is going to be more active anyway. I personally do not like to smoke. I do not like that float feeling. But if I just take the cannabis itself I do not get that float feeling and it still seems to help a lot with other things. I would really like to know how this study was conducted.

 

[Lady Vadalon]

I have been a heavy pot smoker since the late 60's. In 1980 I took the test for entrance into Mensa and score 136 and 142 on the 2 test that night. In 2010 I took another IQ test to challenge a friend about whose was higher. I scored 144 now if there was any truth to the myth that it lowers your IQ you would think it would have showed up by now.
Smoke on brothers

BTW my High School transcripts showed an IQ of 110 my 10th grade year go figure.

But you were older between testing. IQ and smoke just is not a good proof of anything. I hate IQ testing. I was in class a few years ago and was handed a IQ test. Not everyone got the same test. At random part of the class received one for white southern people and the other half received one for African American for the deap south. I live in Oregon.

The IQ paper I got was for the deap south and I did not know very much at all. In fact most of the questions I had no clue about two that still stick out in my mind are the questions about Motor head and chitlins. The point of the papers was not the IQ test it was to show how bias they are or can be. My class was 32 students and 3 were hispanic 29 of us were white.

 

[Mike Wright]

So, you were consuming it and not smoking at all? I agree that if any person using cannabis or not using cannabis and are active and not just laying around the brain is going to be more active anyway. I personally do not like to smoke. I do not like that float feeling. But if I just take the cannabis itself I do not get that float feeling and it still seems to help a lot with other things. I would really like to know how this study was conducted.

The measured effects were specific to oral ingestion, so, yes, I orally ingested that amount every day. I smoked, but only very, very occasionally.

Because of the amount I have read on the nature of cognition, I am well suited to gauge slight changes in my cognitive processes. (In his 1988 book on Neurocomputation Paul Churchland suggests that extensive theoretical knowledge of anything eventually translates into direct perception.) I found at about the 5 month mark that my thinking processes where 'sharper' in certain respects.

 

[Lady Vadalon]

The measured effects were specific to oral ingestion, so, yes, I orally ingested that amount every day. I smoked, but only very, very occasionally.

Because of the amount I have read on the nature of cognition, I am well suited to gauge slight changes in my cognitive processes. (In his 1988 book on Neurocomputation Paul Churchland suggests that extensive theoretical knowledge of anything eventually translates into direct perception.) I found at about the 5 month mark that my thinking processes where 'sharper' in certain respects.

I know that if I really need to focus on what I am studying for cannabis helps my concentration. I try to not use it all the time because I do not want to develop state of dependent learning. But dependent learning can be anything. When I have to take a test or a final I show up in my PJs.

But it is the same if someone is drinking coffee take the coffee with you. I knew someone that drank a lot when studying and when it came time for the test she failed. You can't take beer to class. It sure make for a good debate. Love those things. I myself prefer to ingest just the bud not in yummy food. I do not need any help with the backside.

To me what it boils down to is either, you have it or you don't. Cannabis does not kill your liver or kidneys and to the best of my knowledge won't jell your brain. But you may smile a bit more.

I think that I may have found the white papers on this study. I hope I do not get into trouble posting this link Correlations between cannabis use and IQ change in the Dunedin cohort are consistent with confounding from socioeconomic status