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Teens who smoked marijuana at least four times a week and used marijuana throughout their life saw their IQ drop an average of 8 points, according to a new study.
By Tia Ghose, LiveScience
Teens who smoke marijuana see their IQs drop as adults, and deficits persist even after quitting, according to a new study.
"The findings are consistent with speculation that cannabis use in adolescence, when the brain is undergoing critical development, may have neurotoxic effects," study researcher Madeline Meier of Duke University said in a statement.
The study followed 1,037 New Zealand children for 25 years. Subjects took IQ tests at age 13, before any of them had smoked marijuana, and again at age 38. Throughout the study, participants also answered several surveys about their drug use.
Roughly 5 percent of the participants started using marijuana as teenagers. Those who smoked marijuana at least four times a week and used marijuana throughout their life saw their IQ drop an average of 8 points, the equivalent of going from an A to a B student. The drop was not explained by other drug use, years of education, schizophrenia or using marijuana in the day before the test.
People who eventually quit smoking pot still had lower IQs than they did at the start of the study.
Interestingly, people who picked up the habit as adults had no IQ drop, suggesting that marijuana may not be as harmful to the mature brain.
The findings are the first to associate intelligence declines with marijuana use. Past work linked low IQ and marijuana, but couldn't rule out the possibility that people who choose to smoke pot are inherently less smart than abstainers.
It's not clear why pot is bad for teen brains.
One possibility is that teenagers are more vulnerable to marijuana's effects on brain chemistry, said Susan Tapert, a neuropsychologist at the University of California, San Diego, who was not involved in the study.
During adolescence, neural connections are pruned in the hippocampus and the prefrontal cortex, critical regions for learning, memory and planning, Tapert said.
Those regions may also soak up the active ingredient in marijuana."A lot of the areas that are still developing during adolescent years happen to be the areas with high cannabis receptor density," Tapert told LiveScience.
But those who consistently smoke marijuana may simply make less intellectually stimulating choices at critical points in life.
"What people tend to do when they're under the influence is different than they would otherwise," Tapert said.
For instance, pot users may be less inclined to attend classes or do other activities that give the brain a workout. Getting off track early on can also limit future opportunities and thereby reduce IQ, she said.
Related: 10 Ways to Keep Your Mind Sharp
"Teens need to view cannabis as not an entirely benign compound, but as something that can impair your judgment and might not be great for your brain," Tapert said.
The study is detailed Aug. 27 in the journal Proceedings of the National Academy of Sciences.
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Gotta love these one sided studies that can have a possible but not confirmed linkages. What other factors could be suspect. 1) Diet 2) School attended 3) The test given 4) Time parent spend doing homework 5) environment. The list just goes on and on. Do people really believe this stuff.
The factors you list should have been about the same across the board in the study (on average). What's missing is that they didn't take a group of kids and just give them pot and compare them to a group they didn't give pot, instead kids choose themselves whether or not to smoke pot and it could be that dumb kids choose pot and smart kids don't.
The hysteria never ends with the the Prohibitionists.
So that's what happened to Barack.
Exactly ;-) But what is joes excuse ?
He is just natural.
whom wrote this article....the ghost of harry j. anslinger? what a bunch of bulls$%T!
this reads like a birthday card from the trolls at the DEA. F.U.!
You can not blame fox news ! This is NBC news so according to the liberal rules , it must be true.
While MSNBC is more grounded in reality compared to Faux News that doesn't mean they are perfect. Somebody at MSNBC has an agenda for sure, but I wouldn't throw out the baby with the bath water.
Your icon is pretty cool. Sorry though you can not have it both ways. If the story is on one of the communist news networks it has too be true.
This study wasn't a controlled study so it could be that stupid kids end up smoking pot in the first place while smarter kids don't.
No comment.
LOL!!! HILARIOUS! Having and aunt and uncle who are both psychologists, and pot smokers, I was tested often as a kid and as a young adult. I ALWAYS had an IQ over 150, and have taken a few IQ tests since then... both online versions and those that are professionally done by psychologists. My IQ hasn't changed. I have smoked pot daily for the last 18 years until the last 6 months or so. I have found less time and desire to do so. I make more money than any of my college educated friends, and dropped out of college my freshman year. Now, while I may be a minority, I think there's a whole hell of a lot more to it than just smoking pot. For me, Smoking pot always motivated me to learn more. To absorb knowledge like a sponge. To sit and concentrate on the things that intrigued me. I learned to program while I was high. I learned how to run a business while I was high, and I learned to become successful while I was high. I'm in my 30's and own multiple homes and investment properties. I also learned about real estate while I was high, and started investing while I was high.
The difference here is that I got off my ass and did stuff while all the rest of my friends were out going to raves and parties. I did something while I was on drugs, and they did nothing. I educated myself for free, while my stupid friends racked up school debt and thought they'd make enough money to pay it back in the end, all while spending their free time partying. I just don't believe that this is ALL ABOUT MARIJUANA. I believe that without marijuana, these same people still would have done nothing with their lives, and become consistently more stupid through the stupidity the rest of the world passes on to others.
You're absolutely right. Pot is just the escapist drug of choice for some of the already down and out. But still, you're probably an aberration among the population of smokers. There are exceptions to every rule (or survey) but that doesn't disprove the outcome of a larger sampling.
Gosh, should I turn in my Phi Beta Kappa key?
I'm Listening:
I still have yet to see the proof of the outcome of the larger sampling. Got any?
I may be wrong, (I was once, long ago back in the seventies), but I don't believe IQ tests measure how much you know---I believe IQ represents your ability to grasp and utilize various and sundry concepts. I don't believe that it changes. Your store of knowledge will alter with time, but the facility represented by IQ #s is not going to vary. I can see how a child's store of knowledge may be adversely affected by exposure to the public school system, but not the actual IQ. And, for the record, I have been a recreational, casual and medical consumer of herb for over forty years and it never bothered me at all---botherad allof my all at will---will i be bothered by all---bothered will never all be me------------Weed is the cash cow of the criminal injustice system and there are many on the payroll helping keep the fear going. Lighten up---sit down, relax and catch a buzz! And to the doc from chitown---straighten out that Romney sticker on your Mercedes!
Yup, another completely useless study that doesn't prove anything other than those conducting theses studies have an agenda. I would love to know who supported this organization to conduct this study.
Sorry, but all this has told me is as an adult I can smoke weed and not be affected, and as a teenager I can still smoke, but not as regularly and that if I do additional drugs then MAYBE... there's a chance my IQ will drop by only 8points.
I bet beyond reasonable doubt I could find a handful of folks who smoke like a chimney and have IQ's that surpass 160. Oh wait, I work with two of them.
There goes that research study right out the window.
I hear druggies say they'll get pot legal when the "baby boomers" die off. LOL. That's funny.
I and many of my friends are OLDER then the boomers. And I just bought a 20 year CD.
I've seen a lot of druggies die off when they are young. I doubt any druggie reading this today will be here when the boomers are gone. LOL.
Az - You can't deny that society is changing it's mind slowly but surely. 10 years ago it wouldn't have been possible to get a referendum on a state's docket for legalizing. This year there are 3 states that come November, have proposals to legalize and control like alcohol. Washington, Oregon and Colorado. It's coming, and being a baby boomer myself (actually slightly younger than baby boomer) I don't see how anybody can deny the wind of change. Now we even have cities w/ referenda on legalizing or decriminalizing at least. The war on drugs has been going on for over 40 years now, and it's accomplished absolutely nothing, except wasting over a trillion dollars that could have been much better spent. Do you support the war on drugs? If so, I'd like to hear exactly what benefits have come from it?
To: chicago's eringloriaryan,
Your comment: "people who will complain of my choice of words will mostly be those who use MJ illegally, often on welfare/food stamps, who don't want to hear the truth. They're a big part of why this nation is having an economic meltdown. Social programs and the criminal justice departments are using a HUGE percentage of tax dollars, partly due to drug abuse." is to be challenged. I bet you are a Republican, so you probably don't understand that what causes BIGGER problems than people using marijuana is the constant and continuous disparity between the upper 1% vs the other 99%. The idea that people, who rely on social programs, is the cause of the economic meltdown is simply a delusion. How about corporations that do not pay their fair share of taxes? Or companies who do not pay a liveable wage?
BS......just more right wing propaganda
Wow man, you know what I'm sayin man? Dig it, cool, heavy, take another hit, man, like, right on bro, I hear ya, that is too cool, take another toke man, like, I'm already slidin man, far out, who's the dude? like OK man, I gotta run, a big corporation is waiting for me man, like way out, gotta split, cool man, it was good vibing wit ja, who are you again, man? Far out, I'm reachin ya, later dude!
Way to perpetuate a stereotype, man.
Um....I have a 4.3 GPA. and I smoke daily. Explain that.
Cheating??????
Of course he must cheat...he certainly can't be smart and smoke cannabis, can he now? :sarc off:
Some of our greatest thinkers smoked pot regularily.
The bias against pot is purely for monetary reasons. Or because people have been inundated with negative propaganda, and dont know any better, by those who make a living off pot being illegal (monetary reasons). Whether its the booze lobby who dont want the competition, or law enforcement who will see major cutbacks if drugs were to be decriminalized, to entire areas of the medical profession dedicated to court ordered drug rehab.
There is just as much money in it for those who work in the system, who work to prosecute pot smokers, as there is for the criminal element who sells it. Pot smokers are a cash-cow for both sides. Thats why law enforcement and the legal system is so against legalization. It means job cuts. Especially for sleazy lawyers.
I'm curious... Just who are those "greatest thinkers" you refer to?
Can you provide a list and prove it?..would like to see it please.
Perhaps you should have stayed in school, then you would know. Were you a drop out? Did you go to college? Was alcohol involved with that? Or did you drop out because you couldnt keep up? Perhaps you were just happy in a less skilled job. Its acceptable to want a non-pressure job and life, so dont feel bad if thats your reason. Even though some people will berate you for not achieving your full potential, doesnt mean you were required to do so you know.
hint: Google is your friend. I dont supply lists or do homework for other people.
F4E,
I'm disappointed by your reply. There are lots of good arguments for and against pot-smoking and legalization thereof. You claim some great thinkers smoked pot regularly. I can't think of a one.
In particular, my personal intellectual heroes (Aristotle, Newton, Einstein, Feynman, Friedman, et al) did their greatest works without the benefit of cannabis.
Seriously, of whom do you speak?
BTW, I graduated from a state college without benefit of alcohol or controlled substances.
Ted Turner, Sir Richard Branson, George Washington, Carl Sagan, Ben Franklin, Stephen Jay Gould, Richard Feynman, Kary Mullis, Andrew Weil, Sigmund Freud, Ralph Abraham, Timothy Leary, to name just a few.
The list is huge, I recommend you investigate yourself. Because there are many more.
That seems to have shut them up Freedom...nice job. And like you say, certainly not a complete list.
This article, and the "science" described herein can only be viewed as pure bull@!$%#. There are alot of things that will make you dumber. Reading this article has made me dumber. Reading the comments makes me feel better that there are people here that are way dumber than I am. Not using/exercising your brain is what really makes you a dumbass. Now...one could blame marijuana...or alcohol...or sports...or T.V....or the opposite sex, (all things some folks spend way too much time doing), as the reason one may choose to not use one's own brain...but this study is woefully flawed. If you are stupid...you may want to TRY to think about why you are stupid...blaming your parents or weed doesn't count as actual thought. If you marry someone that is stupid...you may want to get yourself checked as you may be a complete dumbass as well.
I have seen this phenomenon anecdotally before.
I am glad to see a proper study on it, but I am not surprised.
Wow! That is serious. The key to success in modern society is brains. Young people think they're going to live forever and are invincible, but if the study is correct, they need to pay attention. Caveat smokor!
I wish I knew that back when I was a teen. Perhaps I would have done better in college, other than that Ph.D. I got. Imagine how much further I could have gone
That's right.
A PhD is the result of perseverance, not intelligence.
Wow! I never knew some researchers had crystal balls that they could look into to see what the future IQ of the subjects would have been WITHOUT smoking weed! I need me one of those magic crystal balls so that I too, can see into the future!
More propaganda from your Big Pharma Companies that would rather you ingest THEIR chemicals and drugs that has God Knows What in it rather than partake of a natural herb! Don't smoke the weed sheeple....eat it! :)
No offense, but such a biased article. First, IQ's are not static evalutions that are unvariable. Second, alcohol as well as certain foods are harmful to the human brains intellictual capacity... but nothing is mentioned of this in the article or the study. By the way, New Zealand loves the drug money our Federal government gives it to fight "drugs".
Legalize pot and regulate it. It's easier for a teen to get weed than it is to get a beer. Regulate marijuana just like alcohol and underage use is fixed.
This is correlational research and causation cannot be inferred. If it were a robust causal effect, then I must have been a genious as a child. I smoked a ton of pot from age 14 until I was well past 30. I went back to college at 37 and completed a PhD at 50. Makes one wonder how much of the observed correlation is due to factors other than marijuana use.
if you smoke weed go to and chicago's eringloriaryan dope is meth
Smoking pot does not lower your IQ. They probably didn't have that high of an IQ anyways, and IQ doesn't account for EQ. I've known alot of people who knew alot stuff but they didn't have the slightest idea of how to use what they knew, and these were people who had "high IQ's", supposedly. Teenagers have alot of variables going on in their lives besides IQ development.
There are lots of different types of intelligence. Let's take Daniell Tammet for example. Here's a kid with autism who can not only count incredible amounts of digits of pi, he can also see colors with numbers. How many people do you know that can explain why ? I can, but I can't count endless digits of pi becaue I don't want to do so. That doesn't make him any less of a intelligence than my intelligence. It's just different.
I smoke it, occassionally for good reasons. But it doesn't effect my IQ.
For instance, there's noble winning scientist in Russia who won the prize for the theory on the poincare conjecture and there's a flaw in it. If you take a lasso and try to draw it to a single point around a sphere is the basic example, that you can draw it to single point. But if you take a lasso and try to draw it to a single point around a donut supposedly it doesn't work. My observed flaw in that is if you apply the same principals as to why a rocket works in outer space to the end of that lasso that yes it will work if you project the end of the lasso through the hole in the donut to draw it to a single point as opposed to just a single force pulling on one end. I think my IQ is doing just fine, unless you want to argue whether or not I spelled donut correctly.
Most people that I know are aware that most IQ tests are inherently flawed anyways because they work on the assumption that there is somehow some single model of human being and intelligence.
This article is simply designed to promote a prejudice against people who smoke pot like so many other articles. And no, I would not knowing what I do know, say that it would be good for kids but for completely different reasons that have nothing to do with intelligence. Even then there are some exceptions I would say it was OK under the circumstances. But that is off topic.
Been to too many Dunkin Donuts....that's how THEY spell it! :)
Luci,
I think it has affected your IQ enough that you don't know that it has affected your IQ.
You should study IQ. It is highly correlated with success in endeavors spanning the human experience.
You caught my attention with the Poincare conjecture. There's no Nobel (not noble) Prize for mathematics. Conjectures don't have flaws in them - they're either right or wrong. Of what do you write?
I'm guessing that your "better living through pharmaceuticals" has addled your brain to where normal people can't follow your logic. Kids, don't try this at home!