New study suggests marijuana use before age 18 decreases IQ

[+Frank B. Subscriber²]

New study suggests marijuana use before age 18 decreases IQ

NEW YORK -- Teens who routinely smoke marijuana risk a long-term drop in their IQ, a new study suggests.

The researchers didn't find the same IQ dip for people who became frequent users of pot after 18. Although experts said the new findings are not definitive, they do fit in with earlier signs that the drug is especially harmful to the developing brain.

"Parents should understand that their adolescents are particularly vulnerable," said lead researcher Madeline Meier of Duke University.

Study participants from New Zealand were tested for IQ at age 13, likely before any significant marijuana use, and again at age 38. The mental decline between those two ages was seen only in those who started regularly smoking pot before age 18.

Richie Poulton, a study coauthor and professor at the University of Otago in New Zealand, said the message of the research is to stay away from marijuana until adulthood if possible. "For some, it's a legal issue," he said, "but for me, it's a health issue."

Pot smoking is relatively common among American teens. The government reported in June that 23% of high school students said they recently had smoked marijuana, making it more popular than cigarettes.

Young people "don't think it's risky," said Staci Gruber, a researcher at the Harvard-affiliated MacLean Hospital in Belmont, Mass. Gruber, who didn't participate in the new work, said the idea that marijuana harms the adolescent brain is "something we believe is very likely," and the new finding of IQ declines warrants further investigation.

Experts said the new research is an advance because its methods avoid criticisms of some earlier work, which generally did not measure mental performance before marijuana use began.

"I think this is the cleanest study I've ever read" that looks for long-term harm from marijuana use, said Dr. Nora Volkow, director of the National Institute on Drug Abuse, which helped fund the research.

Ken Winters, a psychiatry professor at the University of Minnesota and senior scientist at the Treatment Research Institute in Philadelphia, said the new findings aren't definitive, but they underscore the importance of studying how marijuana may harm young people. He had no role in the work.

Meier and colleagues reported their work online Monday in the Proceedings of the National Academy of Sciences. It was funded with governmental grants from the U.S. and Britain, and a foundation in Zurich.

The study drew on survey data from more than 1,000 people in New Zealand -- everybody born in the town of Dunedin during a yearlong span ending in 1973. In addition to being given IQ tests, they were interviewed five times between ages 18 and 38.

At age 18, 52 participants indicated they had become dependent on marijuana, meaning that they continued to use it despite its causing significant health, social or legal problems. Ninety-two others reported dependence starting at a later age.

Researchers compared their IQ scores at age 13 to the score at age 38 and found a drop only in those who had become dependent by 18.

Those deemed dependent in three or more surveys had a drop averaging 8 points. For a person of average intelligence, an eight-point drop would mean ranking higher than only 29% of the population rather than 50%, the researchers said.

Source: Detroit Free Press

[Charisma Veteran]

I'd be prepared believe this, since most of the people I know who seem like the stereotypical spaced-out dumb "pothead" type started when they were young, rather than the folks who started in university for example who don't seem as affected by it. And a developing mind probably is particularly susceptible... I do wonder, though, is it the time period when they started, or simply the fact that they've been doing it longer?

[Shane Nokes]

Everything I've seen indicates that it has to do specifically with the effect on the developing mind. It affects the ability to form certain types of connections that are used for regular cognition.

By the time you've reached adulthood most if not all of this has been completed and is not as likely to be affected.

[ahhell]

I could see this being true. The brain at that age is still developing and screwing with it's chemistry can't be a good thing.

[Charisma Veteran]

Everything I've seen indicates that it has to do specifically with the effect on the developing mind. It affects the ability to form certain types of connections that are used for regular cognition.

By the time you've reached adulthood most if not all of this has been completed and is not as likely to be affected.

That seems quite logical, based on what I do know (I'll admit I've not done much research on the topic).

[theyarecomingforyou]

While we need more studies before such findings can be confirmed it supports what many already suspected, and I have witnessed quite dramatic personality transformations as a result of heavy use. It may not be a dangerous drug as such - nor do I think it should be illegal - but people need to be aware of the dangers. Personally I will never touch the stuff.

[Nick H. Supervisor]

Eh, I smoked before I was 18 although it wasn't a routine thing for me back then. Now I'm older this study has no effect on me.

EDIT: I should probably say that the reason I mention the above is that while I have have smoked before I was 18, I don't feel that I've been held back IQ-wise. I guess that's because it wasn't a regular occurance though.

[The Laughing Man]

Eh, I smoked before I was 18 although it wasn't a routine thing for me back then. Now I'm older this study has no effect on me.

EDIT: I should probably say that the reason I mention the above is that while I have have smoked before I was 18, I don't feel that I've been held back IQ-wise. I guess that's because it wasn't a regular occurance though.

But how exactly would you know ? How can you gauge yourself if you don't know what your IQ could have been if you didn't smoke? Don't get me wrong this is not a personal attack at all.

Most of my friends who smoked before 18 are literally bums right now , go nowhere in life kinda people with no ambition. It's quite sad to say the opposite for those who smoked after/quit. Most of them at least have a job lol

[EdenHerman]

del

[Nick H. Supervisor]

But how exactly would you know ? How can you gauge yourself if you don't know what your IQ could have been if you didn't smoke? Don't get me wrong this is not a personal attack at all.

Don't worry, I understand what you mean. I guess I should say that when I compare myself to some people that smoked all the time, I would say that I have a job and apartment and what not (i.e. a normal enough life). I also don't feel stupid compared to my friends that have never smoked. However, you are right with the idea that there is no telling what my IQ range would be if I hadn't occasionally smoked. At the end of the day though, I don't mind. I would prefer to have lost a few IQ points when I was younger in the name of having fun, and as I said I am comfortable with my situation today so I don't see a problem with my current IQ level.

[EdenHerman]

Don't worry, I understand what you mean. I guess I should say that when I compare myself to some people that smoked all the time, I would say that I have a job and apartment and what not (i.e. a normal enough life). I also don't feel stupid compared to my friends that have never smoked. However, you are right with the idea that there is no telling what my IQ range would be if I hadn't occasionally smoked. At the end of the day though, I don't mind. I would prefer to have lost a few IQ points when I was younger in the name of having fun, and as I said I am comfortable with my situation today so I don't see a problem with my current IQ level.

having fun for you is feeling like crap?

it may be cool when you smoked it at break time with your friends, but was it so cool when you went into class and put your head down on the table and feeling like crap.

[Hum]

Dope smokers can't even spell IQ

[Nick H. Supervisor]

having fun for you is feeling like crap?

it may be cool when you smoked it at break time with your friends, but was it so cool when you went into class and put your head down on the table and feeling like crap.

Woah. I don't know where that came from. I mentioned that I would smoke with friends once in a while and all of a sudden you've got this idea that I was a pothead that smoked during class time?

And feeling like crap is your opinion. We would have a giggle, and then get tired and have an early night. I also only smoked on the weekend (a Friday or Saturday evening), so in no way was I under the influence when there was something important to be done.

[EdenHerman]

Woah. I don't know where that came from. I mentioned that I would smoke with friends once in a while and all of a sudden you've got this idea that I was a pothead that smoked during class time?

And feeling like crap is your opinion. We would have a giggle, and then get tired and have an early night. I also only smoked on the weekend (a Friday or Saturday evening), so in no way was I under the influence when there was something important to be done.

i'm sorry.

yeah but like, you don't have to hide up that you don't get a bad feeling shortly after smoking it.

[Charisma Veteran]

i'm sorry.

yeah but like, you don't have to hide up that you don't get a bad feeling shortly after smoking it.

eh, it affects everyone differently. For example, it doesn't seem to do much for me at all. Makes me a bit hungry, then maybe a bit sleepy, but it's never really any fun, nor do I feel badly afterwards. I don't even bother anymore... but I think lots of people smoke it without feeling bad after.

[Nick H. Supervisor]

yeah but like, you don't have to hide up that you don't get a bad feeling shortly after smoking it.

I agree, I wouldn't have to hide it if it did happen to me. But it didn't and it doesn't. Sure, we don't giggle as much as we used to, but I would never say that we've felt bad. Remember that there are things that some people can handle, and some things that they can't. If you get a bad feeling then ok, but the last time I felt bad was about 5 years ago and that was only that I felt dizzy and lay down for a few minutes while I reoriented myself.

EDIT: Let me put it this way, if it made me feel bad every time then I would stop. What's the use if you're going to have a bad time all the time?

[EdenHerman]

I agree, I wouldn't have to hide it if it did happen to me. But it didn't and it doesn't. Sure, we don't giggle as much as we used to, but I would never say that we've felt bad. Remember that there are things that some people can handle, and some things that they can't. If you get a bad feeling then ok, but the last time I felt bad was about 5 years ago and that was only that I felt dizzy and lay down for a few minutes while I reoriented myself.

would you smoke weed if it was called "heroin" and all the "nasty" effects about it,etc.

but weed gave you the exact same feeling.

[Nick H. Supervisor]

would you smoke weed if it was called "heroin" and all the "nasty" effects about it,etc.

but weed gave you the exact same feeling.

Did you seriously just try and compare weed to heroin? That's ridiculous. In fact, you've basically said something along these lines:

would you drink orange juice if it was called "bleach" and all the "nasty" effects about it, etc.

I think you and me may as well end our discussion on this subject. Weed is recreational for me and I enjoy it, you don't. Fair enough, we'll agree to disagree.

[EdenHerman]

Did you seriously just try and compare weed to heroin? That's ridiculous. In fact, you've basically said something along these lines:

I think you and me may as well end our discussion on this subject. Weed is recreational for me and I enjoy it, you don't. Fair enough, we'll agree to disagree.

no no, please listen mate.

I am not comparing them at all.

I am saying:

Would you still smoke Marijuana if all the bad things said/going around about Morphine/etc were pointed at Marijuana.

And while all the negative things said about Marijuana , Morphine would be like Marijuana today (how some people think its cool to smoke it ,etc)

[Shane Nokes]

Where is Intrinsica hiding anything? Different people have different experiences.

I have a ton of friends that feel like crap after a night out drinking, but I've never never had a hangover, even after drinking them under the table.

Different bodies, different reactions.

no no, please listen mate.

I am not comparing them at all.

I am saying:

Would you still smoke Marijuana if all the bad things said/going around about Morphine/etc were pointed at Marijuana.

And while all the negative things said about Marijuana , Morphine would be like Marijuana today (how some people think its cool to smoke it ,etc)

There's some very different things about each. Heroin (or other opiates) are highly addictive and cause a lot of issues from a social and health standpoint. Marijuana on the other hand, not particularly habit forming, and doesn't have many of the other detrimental effects on an otherwise healthy adult.

This is coming from someone that has multiple heroin addicts in the family, and several people who smoke pot in the family as well. The adult pot smokers...all work, have jobs, and are chill people. The heroin addicts have all had their kids taken away due to neglect & abuse, constantly in and out of jail for theft, etc.

It's not about perception, it's about verifiable differences in effects.

[EdenHerman]

Where is Intrinsica hiding anything? Different people have different experiences.

I have a ton of friends that feel like crap after a night out drinking, but I've never never had a hangover, even after drinking them under the table.

Different bodies, different reactions.

Yeah I know, and it seems to depend on the type of weed and what you are doing and what not.

I remember the first time I smoked, for the first 5 minutes I was like HI ALL, wow amazing, fun hey all your all great. very happy, love you all so much. (first time in teen years I fealt like I was really enjoying social)

then after 8 minutes I felt like crap, total total crap. that feeling lasted for the rest of the day pretty much (mainly when I went back into class I just felt soooooooo bad, it was just awful. sad/crap and just had it.oh god it was awful.

then the next time I smoked I did not feel crap or happy, I kinda fealt my head was heavyish and was KINDA lifted up a bit or something. but not that great.

overall it was a waste of time and caused you to stop caring.

[Nick H. Supervisor]

Would you still smoke Marijuana if all the bad things said/going around about Morphine/etc were pointed at Marijuana.

And while all the negative things said about Marijuana , Morphine would be like Marijuana today (how some people think its cool to smoke it ,etc)

Ok, I'll see if I can understand your point of view. I'm not going to lie, the wording is causing me issues.

Are you saying the following:

1) Would you smoke marijuana if the publicity on it was negative?

2) Would you take morphine if it had the reputation that marajuana has today?

1) Yes. Publicity is just a form of propoganda. I made the decision in the past to make my own choice and try marajuana, and I would try it again regardless of how widely spread the notion of it being bad for you. I think for myself and do the research.

2) Probably not, for the same reason I mentioned in my first answer. I don't let the world tell me what is right and wrong, I make an informed decision. Regardless of the reputation a drug has, if the evidence points to it being incredibly dangerous then I would avoid it.

[Shane Nokes]

Sounds like either some bad weed, or a bad reaction to too much of it at once. Like anything else moderation is key...

[EdenHerman]

Ok, I'll see if I can understand your point of view. I'm not going to lie, the wording is causing me issues.

Are you saying the following:

1) Yes. Publicity is just a form of propoganda. I made the decision in the past to make my own choice and try marajuana, and I would try it again regardless of how widely spread the notion of it being bad for you. I think for myself and do the research.

2) Probably not, for the same reason I mentioned in my first answer. I don't let the world tell me what is right and wrong, I make an informed decision. Regardless of the reputation a drug has, if the evidence points to it being incredibly dangerous then I would avoid it.

but you did no research back then? no even internet access to tell you all the lies and over rated bull crap about it.

if it was morphine in the "Joint" you would of smoked it right? ;)

Sounds like either some bad weed, or a bad reaction to too much of it at once. Like anything else moderation is key...

Yes indeed good Sir.

moderation .

So your not any anti-medication or anything mate?

cheers

[Calum Veteran]

[. . .]

Weed is recreational for me and I enjoy it

[. . .]

I'm curious as to how many years you've been smoking it regularly, and how often, if you don't mind sharing that information? :) The reason I ask is because I always suspected smoking weed regularly, no matter the age, would permanently lower one's intelligence and ability to think, and I would have thought it would affect one's performance at work (granted, I hadn't yet looked into it, so I didn't assume that would be the case; I just thought it would likely be the case). But the news of this study seems to confirm to me that my suspicions were wrong, and it would be comforting to hear someone state with confidence that they've smoked it regularly for many years and they haven't noticed a negative affect on their IQ, thinking, or work performance.