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Twins Study Finds No Evidence That Marijuana Lowers IQ In Teens (sciencemag.org)
sciencehabit writes: Roughly half of Americans use marijuana at some point in their lives, and many start as teenagers. Although some studies suggest the drug could harm the maturing adolescent brain, the true risk is controversial. Now, in the first study of its kind (abstract), scientists have analyzed long-term marijuana use in teens, comparing IQ changes in twin siblings who either used or abstained from marijuana for 10 years. After taking environmental factors into account, the scientists found no measurable link between marijuana use and lower IQ.
That isn't how twin studies usually work. In this case, one twin decided to smoke marijuana, while the other did not. They weren't assigned roles in an experiment by researchers. Their parents either didn't have a problem with the drug, or they weren't involved in the decision.
The people in Flint, Michigan are about to gain a first hand appreciation of what lead does to cognitive abilities.
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From the study
Standardized measures of intelligence were administered at ages 9–12 y, before marijuana involvement, and again at ages 17–20 y. Marijuana use was self-reported at the time of each cognitive assessment as well as during the intervening period. Marijuana users had lower test scores relative to nonusers and showed a significant decline in crystallized intelligence between preadolescence and late adolescence. However, there was no evidence of a dose–response relationship between frequency of use and intelligence quotient (IQ) change.
Very smart people are not always very motivated people. And vice versa.
Take politics as an example.
There are two types of people in the world: Those who crave closure
I live in the Netherlands, and we've had easy access to cannabis for a long time now. When I studied, a lot of roommates smoked it sometimes, and the heavy users had a few plants in their room. About a quarter of the teenagers have used it incidentally, the rest doesn't really bother with it.
With the experience we have locally we have also seen some issues. The issues are mainly psychological issues - IQ drops haven't been seen but motivation does tend to suffer from long term use. There is a very real link with schizophrenic disorders but it's unknown if people who have the genetic predisposition smoke cannabis because of that, or vice versa - in any case, if you have schizophrenic disorders in the family it is very unwise to smoke cannabis long term, although short term and incidental use may be safe.
Also, an acute psychosis brought on by too much cannabis is a well-known issue and cause of death for young tourists in Amsterdam as well. Usually we have a few casualties each summer because people in a psychosis sometimes think they can fly.
For the majority of incidental users, cannabis is MUCH safer than alcohol. However, there is a minority with genetic vulnerability to cannabis that should not use it at all, and long term use of cannabis (2+ years) is probably unhealthy for a much larger group - and I'm ignoring the wider and well-known effects of smoking here, since you could also drink it (as thee) or eat it (in cake).
I'm not against recreative drug use. It should be decriminalized asap. But it's not as harmless as some people make it out to be, even if it doesn't do nearly as much damage as alcohol or cigarettes.
Therefore, by the (faulty) logic you're using, you're just a cow with a keyboard - osu-neko (2604)
No, most of us aren't familiar with your anecdotes.
You posted an comment so vague it is meaningless. You did not provide anything agreeing with or refuting what was written.
There's nothing to agree with or refute. If you take even a cursory look at the story, you will see that this was not the kind of study that the GP assumed it was.
Teenagers were not subjected to drug use for this study. Adults who had used marijuana as teens were studied.
The first hint was right there in the summary:
If we're studying the effects of marijuana use on teens, and ten fucking years have gone by, then what exactly is the probability that these subjects are still teens at the time of the study?
Go ahead, get out your calculator and I'll wait here for your answer.
You are welcome on my lawn.