Marijuana Smoking Lowers IQ

If you’re under 18, you might want to check out this research before sparking up that fat boy. Report from BBC News:

Young people who smoke cannabis for years run the risk of a significant and irreversible reduction in their IQ, research suggests.

The findings come from a study of around 1,000 people in New Zealand.

An international team found those who started using cannabis below the age of 18 – while their brains were still developing – suffered a drop in IQ.

A UK expert said the research might explain why people who use the drug often seem to under-achieve.

For more than 20 years researchers have followed the lives of a group of people from Dunedin in New Zealand.

They assessed them as children – before any of them had started using cannabis – and then re-interviewed them repeatedly, up to the age of 38.

Having taken into account other factors such as alcohol or tobacco dependency or other drug use, as well the number of years spent in education, they found that those who persistently used cannabis – smoking it at least four times a week year after year through their teens, 20s and, in some cases, their 30s – suffered a decline in their IQ.

The more that people smoked, the greater the loss in IQ…

[continues at BBC News]

majestic

Majestic is gadfly emeritus.

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54 Comments on "Marijuana Smoking Lowers IQ"

  1. There is an element of truth here of course, as anybody who abuses any substance will suffer detrimental side effects and weed will “dope you out” if you use it in copious amounts daily.

    But, that’s not the whole story of course.

    What this article fails to account for are the many creative talents who have used this plant to aid their work… so again, a ridiculous unbalanced article in the mainstream media.

    If a person is sensible, I don’t see a problem. But yes, educate all young people to have a healthy relationship with drugs.

    • “fails to account for are(?) the many creative talents(?) who have used this plant to aid their work…”

      Such as? Who? How? What?

      “I know this guy who is totally successful and he smokes constantly, maaaaaaan… He was so freakin’ smart they promoted him right up the chain to Assistant Lead Night-Shift Cook at Perkins, maaaan… And my other buddy, freakin’ GENIUS, maaaan. He uses weeeeeed to create the most beautiful art, maaaan. I mean, no one really likes it or buys it ‘cept us, but he’s totally gonna make it some day. Genius, I tell ya. …maaaaan. Yeah. For are… Uh. …what were we talking about?”.

      You win. Mainstream media obviously hates successful pot heads.

      • Amilcar Alcanfor | Aug 28, 2012 at 3:20 pm |

        Gee, you’re wonderfull Mr. Murgatroyd!

      • De Carabas | Aug 28, 2012 at 3:27 pm |

         Carl Sagan. Now go crawl back under a rock.

        • You’ll have to do better than one name! Outliers are statistically irrelevant (unless they side with your viewpoint, right maaaaaaan?). You can’t dismiss a study based on one individual result. Good try though! lolol

          • SnarlPagan | Aug 28, 2012 at 5:47 pm |

            Actually he wins.  You asked for a counter-example, and he provided.

            Now carry on your delusional anti-drug rantings.

          • Calypso_1 | Aug 28, 2012 at 5:53 pm |

            Outliers are not necessarily statistically irrelevant.  They may, among other things, indicate that the theoretical model predicting population distribution is flawed.

          • Thank you for being the voice of reason in this thread. 

          • A few musicians I know who work in a studio local to me and are wicked guys… that’s wicked, as in, good 😉

      • Louis Armstrong.

        Robert Anton Wilson.

        • Keep goin’, Cheech! You have to come up with enough results to negate a scientific study of 1000 people! Maybe if you just–

          …Wait a minute… I’m being told… Oh, is that right? Really? Gosh dang-it, they’re gonna be– Ok. Ok..

          Well kiddos, I was just informed that cherry-picking outliers from all past and present human beings world-wide is not in any way relevant to a proper study. So… You’re wrong. They’re right. You lose. Game over.

          Geez… I’m sorry guys. I was really rooting for you. Sorry about your IQ. It’s not so bad though. That Forrest Gump guy did alot of amazing things on a lower-than-average IQ. Cheers!

          • You’re so ignorant and brainwashed it’s almost sad. I’m an entertainment industry professional with a 166 IQ who makes well over 1m a year, and I promise you that nearly everyone in Hollywood smokes regularly and are just as successful as I am — if not MORESO. And as it has become more accepted, most of these people have used weed to successfully treat their depression, anxiety, sleep disorders, all without the need for pharmaceutical company crap which you clearly support.

            But you go right on drinking your stress-inducing drugs every day (caffeine) or drowning your sorrows in alcohol, or popping your prescription meds while obliterating your brain cells with hours of television. I’m sure those won’t have ANY detrimental effects to your mind or body whatsoever. You and the rest of the sheep.

          • Hi. I’m an entertainment industry professional with a 197 IQ who makes well into $11M a year, and I promise you that working in Hollywood and being included in a certain income bracket directly correlates to intellectual ability and drug use. My opinion matters. You see, on forums and the comment sections that follow articles, my random testimonial can 100% destroy a peer-reviewed study that spans decades. Listen up readers: When faced with accepting what a study says or listening to biased commentary promoting a highly complicated conspiracy to smear the good name of a narcotic substance, ALWAYS LISTEN TO THE COMMENTS. Smart people don’t wear lab coats and spend decades gathering facts, THEY SMOKE DOPE AND PRODUCE THE MIND-NUMBING GARBAGE YOU SEE ON TV AND IN THE MOVIES. Yeeeeeehaaaaaawwwwwwwwwwwwwwww ‘Merica!

          • mannyfurious | Aug 29, 2012 at 12:09 pm |

            Besides, picking Hollywood as an example of where intelligent people tend to congregate is stupid as fuck….

          • lab coats also create all the weapons and thats sooo smart

          • i mean, i hate statistics as much as the next guy, but 1000 people? That’s not really THAT many more than 5 or 10 when considering significance.

          • Calypso_1 | Aug 29, 2012 at 9:04 am |

            I need to correct you on this.  It is that much more significant.  What we are talking about is appropriate sample size for a population, confidence interval (margin of error) and confidence level (which in most studies is 95%).
             
            The population of New Zealand is 4,405,200 of which 13.4% are regular cannabis users (UN report).  This is 590297 people.  1000 people sampled from this population at 95% confidence produces a margin of error right around 3%.  Studies are rigorously designed to include the number of participants and methodologies needed to produce accurate statistical results.
            Also 1000 people in a 20 year longitudinal study is a huge study of this nature – granting that one of the primary difficulties of longitudinal studies is managing sufficient sample sizes over such a long period.

          • (yea i realized that was kinda a stupid comment seconds after posing it but…)

            not that i’m disagreeing with you, or even contesting the results of the study,  but if you think about it, isn’t a 95% confidence level impossibly absurd for a longitudinal study? I get that you can use statistical theory to attempt to justify such confidence, but when you’re gathering data over 20 years, you’re also inadvertently gathering 20 years of noise.

            I kind of doubt the confidence level was that high. Typically with messy human factors, confidence levels as low as 60(and lower?), can get reported with as much excitement as this article. Its amazing how much we “know” from psychology and other social “sciences” because the bar was set so low.

            Also, This:
            http://xkcd.com/882/

          • Well, I can clearly see you have “average” IQ. No one is going to change what they are doing because of your tasteless ranting. Plus a study on such a controversial topic can not be trusted. There needs to be multiple studies.  Stop trying to get attention. No one cares what you think about anything.

      • you are annoying. no one speaks like that. you obviously aren’t very versed and capable, socially speaking. 

      • coiled embrace | Aug 28, 2012 at 9:02 pm |

        Bruce Lee.

      • One of my favourite blokes – Alan Moore 🙂

      • thomas jefferson

  2. There is an element of truth here of course, as anybody who abuses any substance will suffer detrimental side effects and weed will “dope you out” if you use it in copious amounts daily.

    But, that’s not the whole story of course.

    What this article fails to account for are the many creative talents who have used this plant to aid their work… so again, a ridiculous unbalanced article in the mainstream media.

    If a person is sensible, I don’t see a problem. But yes, educate all young people to have a healthy relationship with drugs.

  3. lol @ stoner butthurt

  4. Tchoutoye | Aug 28, 2012 at 3:49 pm |

    On a more positive note, one of the researchers stated that cannabis is safe for over-18 brains, so all you adults can light up without a worry.

    Unfortunately the article doesn’t say if this is peer reviewed research.

    The recent study relating cannabis to psychosis (the medical term for being stoned, but with added negative connotations) turned out to be conducted by researchers on the pay roll of the drug company producing the painkiller Advil (ibuprofen), now owned by Pzifer. Of course the researchers fraudulently declared “no conflict of interest”, based on the lie that cannabis has “no medicinal properties”, whereas in practice many thousands of people use cannabis as a painkiller.

  5. Dat IQ

  6. I think some healthy scepticism is in order here. They assessed the subjects as children before they started smoking and yet, by the time they were 18 they had been smoking for years. How old were these children they were discussing marijuana use with? This was obviously not passive observation and there is no accounting for the testers effect on the test subjects. Perhaps children who are suggestible tend to have decreasing IQs. This study’s conclusion does not conform to any accepted scientific method, or even basic logic for that matter. The cause and effect are not even addressed much less established. The peers who reviewed it must have been stoned.
    Here is a conclusion that, based on these results is just as valid. People with decreasing IQs are more prone to use marijuana.
    “A UK expert said the research might explain why people who use the drug often seem to under-achieve. ” More likely it merely demonstrates underachievers tend to use drugs.

  7. WistonSmith | Aug 28, 2012 at 5:36 pm |

    Fluoride drops IQ, not cannabis. I’ve been regurarly smoking pot for 5 years. I am 18 now.  I was head of my classes through highschool as well as in college, presently. So don’t give me that bullshit. It’s just another way of big pharma, or whoever benefits from pot being illegal, to spread false news and propaganda. 

    • NOT MY IQ!!! NOOOOOOOOOOOOOOOOO!!!!!! I’ve invested so much in my mental tally wacker!!!!  How will I feed myself, obtain lovers or my own sam’s club membership!!!!!!!!!  I feel the crushing need to tune into the OWN network and be soothed back to sleep.  Ahh if only I owned things, then life would be complete, I could rest my weary head on Oprah’s omphaloi and nod comfortably back to sleep….. So someone done hacked my facebook….

    • Calypso_1 | Aug 29, 2012 at 11:59 am |

      Is that the fluoride naturally found at high levels in very well defined ground water locations or the fluoride that is in municipal water sources at much lower level?    

  8. Watch Cheech Marin on jeopardy.  All the proof I needed.

  9. Beatitude Sputnik | Aug 28, 2012 at 6:29 pm |

    Fuck it, I can afford to lose a few points here and there.

  10. DeepCough | Aug 28, 2012 at 6:53 pm |

    Irony: cannabis seeds, which are rich in omega fatty acids, can improve your brain function.

  11. The more that people smoked, the greater the loss in IQ… bollocks the more stone i get lol

  12.  Bill Hicks – Drugs          http://www.youtube.com/watch?v=X5FkYhrKRvU&feature=youtu.be

  13. Multidimensionalbeing | Aug 28, 2012 at 9:25 pm |

    This is one the MAIN reason I smoke cannabis. I want to lower my IQ so I can coherently function in a society of retards. If I don’t smoke cannabis, people don’t understand a goddamn thing I say.  

  14. Ceausescu | Aug 28, 2012 at 11:40 pm |

    I what ?

  15. One thing that’s rarely considered in these sorts of studies is the individual. No doubt pot can have a negative impact on the developing brain, but to say it lowers the users IQ is simply false. This is an over-generalisation. From personal observations of friends who smoke it, I can say that the individuals who are intelligent and creative are not affected in a negative way from smoking, in fact they are often more intelligent than people I know who don’t, and never have smoked pot. There is the other group however, who aren’t particularly bright anyway and smoke only to get high, (they’ll usually smoke till they green) these are the guys who fit into the category of this study, but that is only one group of stoners, not every pot smoker in the world.

  16. TruthVybes | Aug 29, 2012 at 3:47 am |

    lol “iq”. I don’t think ‘intelligence’ should be classified when you’re a few ‘ingelligences’ away from stepping into other worlds. screw erudition when you have insight and imagination. That’s the secret.

    • TruthVybes | Aug 29, 2012 at 3:48 am |

       HOwever I must agree that its up to the user. Besides, braincell growth is an aspect of the mind and nothing else. Use it or lose it, simple as that.

  17. zombieslapper | Aug 29, 2012 at 6:37 am |

    In the fourth grade I scored a 127 on the IQ test we were given. At age 25, after many years of regular pot smoking,  I took one of those online IQ tests and scored a 127. Days later I took the test again while under the influence of marijuana and scored a 123.

  18. A friend who is a civil servant and a very high earner.

    Erm… more?

  19. A final note for all of you smokers with your panties in a twist: I am FOR the legalization of marijuana. What I am NOT FOR is the glorification of marijuana and denial of its detrimental effects simply because it is something that you enjoy passionately. You have to recognize and admit the negative effects of the substance. If you can’t be honest about what you are promoting, you make it far easier for the opposition to humiliate you and halt your progress. You hippies make it sound like a miracle snake-oil treatment.

    If alcohol was up for debate, and was defended and promoted in the same manner as marijuana is currently, we would be spouting the “medical benefits” of alcohol. Stress reliever! Relaxation aid! Pain reliever! Sleep aid! Can be used to treat social anxiety disorder! Helps me stay sexually attracted to my now overweight wife! Great for cancer patients! Mind expanding! I come up with me BEST IDEAS DRUNK! I’M A SUCCESSFUL MILLIONAIRE AND I DRINK ALL THE TIME!!

    You’re only embarassing yourselves and hurting your cause. I suggest a different approach: If I can go out and purchase a 12-pack of beer, drink them all and become completely intoxicated, harming my body and impairing my judgement, why can’t I step out on my back porch and smoke a joint, harming my body and impairing my judgement? It’s exactly the same. Both have beneficial effects and clear negative effects, but it is my right as an adult to choose whether I partake or abstain from one or the other.

  20. WTFMFWOMG | Aug 29, 2012 at 7:21 pm |

    Well, duh. Any mind altering substance a child uses before their brain has finished developing will have a more significant influence on the rest of the person’s life than when the brain is “fully” formed by around the mid-20s or so. Does this mean we should ban consenting adults from using cannabis? The fact is that the black market has no minimum age requirement, plus the forbidden fruit has the sweetest taste, so I can only conclude that current prohibition policies have a detrimental effect on the development of the human brain. We should stop blaming the substance for the behavior.

  21. WTFMFWOMG | Aug 29, 2012 at 7:21 pm |

    Well, duh. Any mind altering substance a child uses before their brain has finished developing will have a more significant influence on the rest of the person’s life than when the brain is “fully” formed by around the mid-20s or so. Does this mean we should ban consenting adults from using cannabis? The fact is that the black market has no minimum age requirement, plus the forbidden fruit has the sweetest taste, so I can only conclude that current prohibition policies have a detrimental effect on the development of the human brain. We should stop blaming the substance for the behavior.

  22. Apathesis | Aug 29, 2012 at 10:17 pm |

    Religion’s far more detrimental to IQ levels than weed.  Just look at Uganda… or the USA.

  23. If anything alcohol causes some sort of retardation. When I smoke I can at least walk around, talk to people, function normally and if I’m under some deadline, actually be productive. In fact yesterday I reorganized my basement studio while smoking some very nice purple weed of a quality I have not had in a long time . I was waiting for a while to get the will power to tackle the mess and didn’t find it till I smoked that high quality pot. When I am drunk, I can’t walk, talk, work correctly, I get sick, do things I regret and have a bitch of a hang over the next day. Imagine if alcohol was illegal and pot (which is the more mild of the two substances) were all over; a beer run would would be waaay different and so would society.  

  24. Roger Mexico | Aug 30, 2012 at 2:20 pm |

    Everyone gets that they found this effect only if you smoke heavily before age 18, right?

    That’s basically scientific confirmation of common sense–while your brain is still developing you can cause permanent damage by exposing it to certain chemicals.  (See also: fetal alcohol syndrome.)

    Examples of “successful” adult stoners don’t disprove it at all, unless they started smoking at age 13.

    • Roger Mexico | Aug 30, 2012 at 2:21 pm |

      As in, this is a case for a minimum age of use, not blanket criminalization.  Just to be clear.

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