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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.
You don't have much experience thinking about medical issues, I take it?
Science cares about reality.
Your fiction of "what if" and fear of the unknown is how we ended up with prohibition in the first place. This attitude that "if it feels good it must be bad for you" is puritan, religious non-sense.
Marijuana is common place is society, and scientifically it has been shown to be rather benign.
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.
If the kids are 16+ then the parents' opinion isn't too important, is it?
And the reason for doing it? Well, in the US, billions upon billions of dollars has been spent on detecting, prosecuting and jailing the users, growers and importers of this more or less (for the vast majority of users) harmless plant. And if drugs policy is to be based on facts then this sort of fact is just one more reason to give it up already and let adults decide what plants they'd like to benefit from.
It was likely survey based. I.e. they found identical twins and asked them if one used and one didn't, and if so, they evaluated them afterwards.
Anyways I'm kind of disappointed that they only looked at IQ, as to me it's a meaningless figure whose only purpose is for "I am more smug than thou art" clubs like Mensa. I'm more curious about other functional measurements both physiologically and sociologically (i.e. how did they vary in terms of career success.) There's some evidence that marijuana can improve both, as well as evidence that it can harm both.
I knew many very smart people who did marijuana. I would have thought most of them would have done more with their smarts but I see them now and they're mostly just getting by. They are happy for the most part though. Thinking about it I'm not sure if it's such a bad thing.
You didn't read TFA. The study is of teenage twins who previously had/hadn't smoked marijuana (ie they were given questionaires, and twins were then selected for IQ testing if one had smoked and the other hadn't) not of twins who signed up to take part in a controlled experiment.
Parents either had nothing to do with it, or simply failed to prevent one of their twins taking the drug.
The study is probably, to a certain extent, flawed because of that methodology, but without commiting ethics violations of the type you describe, there's probably no way to get a more accurate result.
You are not alone. This is not normal. None of this is normal.
The people in Flint, Michigan are about to gain a first hand appreciation of what lead does to cognitive abilities.
I am Slashdot. Are you Slashdot as well?
You are correct
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.
There seems to be an implication here that twins have identical IQs. I don't think that is valid and it strike me as more likely that the twin with the lower IQ is the one who elects to abstain from wacky weed and the twin with the higher IQ is burning out brain cells until they get down to their sibling's level.
I'm an American. I love this country and the freedoms that we used to have.
Stoners become stoners because of lack of motivation, not the other way around.
Exactly contrary to my observations. Stoners become stoners mostly for social reasons - it's a social activity. For many, it alters them - bright, motivated, active people can become listless lumps. I've seen it in young teens, people in their twenties, less so in older adults who start.
They're paranoid because they engage in an illegal lifestyle and the law is literally out to get them.
Most of them aren't the least bit worried about the cops unless they're distributing. And the paranoia tends to be about many things, if not most things they deal with. It's seen in personal interactions (straining friendly and family relationships over imagined distrust and betrayal), etc.
You know this, you're just trying to wish it away.
Don't disappoint your bird dog. Go to the range.
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
They look basically the same. It turns out that marijuana doesn't turn your brain into a fried egg. Who knew?
This just in: Having a twin provides a natural immunity to the IQ-reducing properties of marijuana.
"When I was a boy of 14, my father was so ignorant I could hardly stand to have the old man around. But when I got to be 21, I was astonished at how much the old man had learned in seven years." - Mark Twain
Prove anything by multiplying Huge Number times Tiny Number
And if drugs policy is to be based on facts then this sort of fact is just one more reason to give it up already and let adults decide what plants they'd like to benefit from.
Indeed. There is a real problem when the biggest detriment that people can identify for using an illegal drug is the very fact that it's illlegal. When the primary concern isn't that the drug will kill you, put you in the hospital, give you organ damage, make you crazy, or make you dependent upon it, but is instead that you'll be fined or tossed into jail, something has gone horribly wrong.
When you have people taking 'bath salts' instead of cocaine, which has a much higher chance of, I don't know, chewing somebody's face off, because the latter is illegal as well as the former, but the 'bath salts' are more accessable for those that would use drugs, we have a problem.
I don't read AC A human right
The "safety" argument relative to drug legalization is huge red herring designed to drag legalization proponents down the path of needing to claim that marijuana is safer than tap water, or worse, into wild and unproven claims of its medical benefits.
The results of marijuana's relative safety have been in for years -- you can't really overdose on it and decades of mass use have failed to show any significant signs of problems in the general population. This is more than we can say about alcohol, acetaminophen, anti-depressants and whole long laundry list of substances that are legal and easy to get.
The REAL argument is that the public policy of marijuana criminalization has been an abject failure. We've spent trillions of dollars on prohibition on it and all we have to show for it is a complete dismantling of our constitutional rights, corruption of a law enforcement system that has produced an epidemic of civil rights abuses quite often enabled by the elusive pursuit of marijuana users (you didn't think they wanted to stop you for a traffic offense, did you?), an erosion in public respect for laws, almost certainly a disregard for the graver risks posed by other illegal drugs, and a criminal justice system that has ruined thousands of lives and built massive criminal enterprises
What we don't have to show for it is any reduction in marijuana use or availability. As a matter of public policy it has failed in its goals and produced a plague of horrific side effects.
This is the argument that needs to be made. The safety issue is a total and complete distraction.
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.
Yes, it's weak methodology, but better than nothing. And if there was an impact from marijuana use, you'd expect there to be some indication, even though the methodology would make it difficult to quantify how extensive it is. The fact that they found no significant variance in scores indicates that's because there is no effect....or the vast majority of the 1588 participants lied about their drug-use, for no reason.
Never let a lack of data get in the way of a good rant.
Hmm, so similar IQ but lower crystallized intelligence, does that imply that they had higher fluid intelligence? Because somehow, despite their lower crystallized intelligence, they ended up at a similar IQ.
Only I can judge you.
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.
The jumpers are mostly mushroom users.
If construction was anything like programming, an incorrectly fitted lock would bring down the entire building...
Cannabidiol (CBD) and tetrahydrocannabinol (THC) are different thngs. THC is psychoactive, CBD is not.
I've seen plenty of people who don't smoke weed become listless lumps, especially teens and young adults. I've also seen plenty of stoners become excellent writers, artists, and musicians, as well as teachers, programmers, etc..
I think the big problem here is reliance on any test intended to show off levels of intelligence. Many of the cheaper, simpler to administer tests vary wildly in both consistency and accuracy.
Most US schools rely on a specific test to determine gifted/intelligence level. Its cheap and easy to do and doesn't take long. Its primary problem is that in the case of very gifted kids, the test results reverse themselves and may even indicate that a very introverted, very intelligent kid is well below average in intelligence. Then you give the same kid that same test a month later when they're focused and interested in the test and you get a completely different result.
So if you want to show in a study that average scores are lower, use the cheap test. If you want to show higher average scores, use the expensive long tests that capture all of the kids with IQ's over 125 instead of showing them at 80-90.
As far as the original story, I was a regular 'user' in my 20's and dabbled with it infrequently for 30 years. I don't think it reduced my intelligence but it sure does cut into motivation and aggression. One interesting metric I've seen was getting my social security statement a few years ago which showed my annual income since I was a teen. It goes up smoothly and sharply until about the time I started smoking pot. Then it flies level for about five years until I gave it up at which point the income numbers resume the same sharp upward line.
It'd seem to me that the last thing a teenager needs is less motivation and less interest in doing things.
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.
It's a sad comment on our society where we are so worried that there might be some natural substance that makes people feel good that before an effective drug can be approved the feel-good properties have to be removed.
You are welcome on my lawn.
It's the same society that flipped it's shit when someone invented a vaccine against a virus that causes cancer, for much the same reasons.
If I have been able to see further than others, it is because I bought a pair of binoculars.
I had assumed that was "pot doesn't make you stupid, but stupid people are more likely to smoke pot", but maybe I misunderstand.
Socialism: a lie told by totalitarians and believed by fools.
What we're discovering is that everything they said about it is a lie. It was started by Richard Nixon, to use as a tool against the evil jazz musicians. It was perpetuated by entrenched interests like the for-profit prison system that is designed to maximize recidivism and can force its captive labor population to work for 75 cents a day. It is by far the biggest crime committed against the American people, with a financial impact in the trillions. And it is the perfect crime -- no one responsible for it or who profited from it will ever admit they were wrong, much less be held accountable for their actions.
I'm trying to teach myself to set people on fire with my mind... Is it hot in here?
So you want the arbitrary metrics they used to be a different kind of arbitrary?
That is not what he said. He said they should report things like income in addition to IQ. My dope head friends don't really seem to be particularly stupid, but they sure seem to be apathetic and lacking in ambition. So it would be interesting if that was measured and quantified along with IQ.
I firmly believe that a great number of people get some kind of relief from what ails them from marijuana.
That being said, there are a lot of pro-legalization people who respond to challenges made as to its safety with a litany of medical claims that sound little different than the claims made by all manner of herbalists and charlatans.
It's a weak tactic that's not well validated scientifically and ultimately ends up making legalization advocates just sound like hippies down at the co-op.
But like I said, I really do believe that there are significant medical uses for marijuana, I just don't think they've been scientifically validated enough to use as a strong argument for actual legalization.
I know that some legalization advocates are willing to more or less settle for California style "medical marijuana" legalization, but opponents are right to label this as something of a sham and at worst, you might end up with the kind of "medical" legalization like we have in Minnesota with all kinds of strings attached that doesn't really help many people (like literally not many people, they capped participation and enormously restricted access).
And that kind of legalization doesn't really solve the many huge problems with criminalization.
Adults who had used marijuana as teens were studied.
No, adults who SAID that they had used marijuana as teens were studied. How many of them were honest about it?
Seeing how the middle class is all but gone and most of those teens are destined for minimum wage jobs for the rest of their lives, anything that helps make that more bearable helps both them and the society at large.
Forget magic. Any technology distinguishable from divine power is insufficiently advanced.
I understand your point, but as long as alcohol is legal, all the discussion about cannabis being "not as safe as some people make it out to be" are meaningless.
"The agriculture ministry is not in charge of Gundam" - Japanese ministry official.
My dope head friends don't really seem to be particularly stupid, but they sure seem to be apathetic and lacking in ambition.
I'm extremely lazy and exhibit all the signs of a pothead, but I don't smoke. I wonder if I did get on it, would my natural lack of ambition be blamed on the weed?
Maybe your couch bound friends were like me already that way inclined, and figured smoking pot makes the couch an even more enjoyable place to be?