A False Link Between Marijuana and Mental Illness

The article published today in “Health News” makes the claim that smoking marijuana is “linked” to early onset of mental illness.

However, although the article implies some sort of cause and effect, that conclusion has no scientific basis. In fact, the authors of the study don’t even bother investigating whether marijuana use causes mental illness or if people with mental illness have a higher rate of smoking marijuana than the general public.

If marijuana caused mental illness, then cultures that have a higher rate of marijuana smoking than the U.S. should have a higher rate of mental illness. But in fact, the opposite is true. Cultures with higher rates of marijuana consumption have lower rates of mental illness than the United States. This would indicate that rather than marijuana causing mental illness, as your article implies, it is people with mental illness who are self medicating with marijuana in order to alleviate their symptoms.

This (more correct) reading of the data, however, does not fit the narrative being presented by the politicians who are making their careers by “getting tough” on marijuana smokers, nor does it fit the narrative of the manufacturers of the currently legal psychotropic drugs, like Prozac and Zoloft, who stand to lose billions of dollars if medical marijuana is legalized, and who funnel millions of dollars to those politicians who present their dubious science as fact.

Had your newspaper even taken the time to Google the Archive of General Psychiatry, you would have found that the “study” you cited was conducted by the “Genetic Risk and Outcome in Psychosis (GROUP) Investigators,” who publish only articles against medical marijuana. That alone should raise a red flag to anyone with a basic understanding of scientific research. When someone conducts numerous studies and publishes many articles that all draw the same conclusion, whether the evidence leads to that conclusion or not, the critical eye should suspect some ulterior motive at work. It’s not possible to keep an open mind when you have an axe to grind.

William Smith, Baltimore

– Letter from The Baltimore Sun.

Psychosis Triggered by Smoking Pot? Marijuana Study Says Yes

by CBS News

(CBS) Advocates of medical marijuana say pot has all sorts of health benefits. Maybe so, but a new study from Australia suggests that smoking pot can drive some people crazy – or at least make them go crazy sooner than they would have if they had never picked up the pipe.

The study, published online in “Archives of General Psychiatry,” shows that potheads develop severe mental illnesses like schizophrenia about 2.7 years earlier than people who don’t use marijuana.

The link between smoking pot and mental illness appears strongest in children 12 to 15 years of age, Reuters reported. They develop mental illnesses that might not have shown up until their late teens or twenties – if they showed up at all.

“The results of this study provide strong evidence that reducing cannabis use could delay or even prevent some cases of psychosis,” study author Dr. Matthew Large, of the University of New South Wales, said in a written statement.

What explains the link between marijuana use and severe mental illness? One possibility, according to Dr. Large, is that pot smoking actually causes psychosis. Other possibilities, he said, are that pot might hasten the onset of psychotic symptoms in vulnerable people – or make symptoms of psychosis worse.

But other scientists say there are alternative explanations.

Michael Rice, a psychiatric nurse practitioner at the University of Nebraska Medical Center in Omaha, told HealthDay that people who are predisposed to schizophrenia might gravitate to smoking pot because it has a beneficial anti-inflammatory effect.

Whatever the explanation, Dr. Large and his colleagues are eager to publicize the risks pot smoking poses to young children, writing “Even if the onset of psychosis were inevitable (for a particular individual), an extra two or three years of psychosis-free functioning could allow many patients to achieve the important developmental milestones,” MSNBC reported.

“I’m not a marketing expert,” Large said, “but we have to find a way to tell young kids to hold off.”


– Article from CBS News.



  1. Anonymous on

    …even when its posted on some “alternative” website and you may agree with its sentiments.

    As far as this “cultures with higher rates of marijuana consumption have lower rates of mental illness than the United States,” what countries are you talking about?

    There are only two possible candidates: Australia and New Zealand. While I failed to find statistics for New Zealand, Australia certainly has a higher incidence of the schizophrenic illness specified by the study, with 1.3% of the population suffering (285 000 sufferers in a population of 21 mil.) compared to 0.7% (2.2 mil. sufferers in a population of 307 mil.) in the United States.

    Further, the study merely states that marijuana can provoke said illnesses in those predisposed to develop them, and that some of those who do as a result would not necessarily have done so without exposure to the drug. Thus, your idea that the percentage of sufferers would dramatically change because of varied cannabis use is flawed, as the percentage of the population predisposed to psychosis would remain the same.

    As far as this “self-medication” theory goes, take this excerpt from the study: “Our findings do not support the view that people with a propensity to develop psychosis at a young age are simply more likely to use all substances, because alcohol use was not associated with a younger age at onset.” Alcohol is just as able to dull the senses and blunt the edge of mental illness, so a correlation between its use and these illnesses would just as likely exist.

    As far as this “Oh, just another Big Pharma’ ploy to stop the pot” and “God, the authors are mega-biased; the journal is just a vehicle for corporate interests” moaning, don’t kid yourselves. First, here’s the study:


    Now on that page search the text “Genetic Risk and Outcome in Psychosis (GROUP) Investigators” and you’ll notice those words do not come up. I don’t know where he’s got the idea that they authored the study; it was conducted by researchers at the University of New South Wales, so we can forget that nonsense.

    Second, notice Dr. Large, one of the study’s chief authors, stating “I’m not a marketing expert, but we have to find a way to tell young kids to hold off.” Hold off. Until their brains have fully developed. So they don’t have an increased likelihood of developing debilitating mental illnesses in line with his analysis. These are not the ravings of a prohibitionist, but those of a reasonable man.

    The fact is that this study does not weaken but bolsters the case for legalisation. Marijuana can have detrimental effects on the adolescent mind, so what do we do? Rule it illegal so that criminal operators, more than happy to sell copious amounts to children, enjoy a monopoly of the market. Sheer madness.

    Alcohol is currently harder for teens to acquire than pot because it’s legal and sellers risk their businesses in supplying it to them; drug dealers risk the same penalty whether they sell to a middle-aged man or a minor.

    Think critically and don’t believe any old nonsense, that’s my point. Being for the legalisation of marijuana doesn’t necessitate you believing it be some flawless, magical substance, capable of everything good and responsible for nothing bad.

    Alcohol hard to get than pot:

    Some of the statistics I used:

  2. Anonymous on

    i agree with your views , i would hope that the powers that be on the reserve let you start growing the herb for ceremonial purposes as well as harm reduction for your neighbours , getting the people off the prescription drugs is very important but i think it could work if you had an alternative .
    good luck

  3. Anonymous neechie on

    I am an economic development officer for a First nation, the membership is living everyday in oppression-by racism, discrimination, poverty, dictatorship and an uneducated council, corrupt, and lack the skills of long–term planning.
    A recent drug bust, that involved two members of a council, on a near-by first nation, involved the trafficking of pills.
    The situation has moved to a model of “east-hastings”, where methadone, needles, crushing up pills to snort, prostitution, theft, shop-lifting, and now children as young as 16 are starting to “slam” these chemicals up there arms. The graveyard is full of people who have overdose and died, not from cannabis use, but from prescription pill abuse.

    this has reach proportions of an epidemic, a crisis- however….
    doctors take full advantage of this situation…one particular doctor- Dr. Davies….who has been here the longest, should have the understanding of the community but continues giving out these pills-free through health canada- very little paper work to fill out, and dispense that day- to the addict….

    Pharmaceutical companies are making huge profits as well as the doctors…on opiates and methadone program of failure…like the cycle of consumerism..so is the cycle of prescription pill addiction…

    the issue I have is how easy it is to access these pharmaceutical products….but yet to get medical marijuana is like filling out a “phone book”. and then sending that into health canada, where that might take up to 6 months for approval!?!? WTF….huge discrimination for those who wish to stay away from pharma products…

    I am so disgusted at pills, that I never want to take them…
    I am living proof, that i know cannabis has health benefits…for depression, physical pain, reduction in high blood pressure, and for myself-arthritis

    when is the last time you heard of someone dying or overdosing on cannabis, and when is it the last time you heard of someone overdosing on slamming pills up their veins?????

  4. Anonymous on

    Dr’s are getting huge bonuses from the powers that be.. for diagnosing people with mental illness. They want us all drugged up on Prescriptions or locked up in the mental house. Of course they are saying this medical marijuana is their worst enemy. facts speak so do the people

  5. Anonymous on

    Dr’s are getting huge bonuses from the powers that be.. for diagnosing people with mental illness. They want us all drugged up on Prescriptions or locked up in the mental house. Of course they are saying this medical marijuana is their worst enemy. facts speak so do the people

  6. Anonymous on

    Who was advocating Cannabis use for 12-15 year olds anyway? If that’s the worst thing they can find about Cannabis, even if it turns out to be true, then it beats every pharmaceutical in the free world, including aspirin which will put holes in your stomach lining or kill you outright if you take one measly bottle at once. Schizophrenia only affects about 1% of the population anyway? How many of those could be linked to Cannabis use at 12-15 years of age? It would be a ridiculously low percentage of the population. They want to throw people in jail and invade their homes just because of maybe .001% of the population possibly getting Schizophrenia a few years earlier. Kind of an overreaction, isn’t it? Why the huge concern about such an insignificant demographic? Schizophrenia won’t kill you. What if they drink alcohol? I figure they will develop liver disease WAY sooner than they would have otherwise. There are a whole lot more than 1% of the population actually dying from alcohol and tobacco. Better put them in the CDSA too then.

    Something that only has negative effects on less than 1% of the population has never been a major concern to the government in any other case. Why the exception just for Cannabis? The vast majority of Cannabis users have no ill effects whatsoever. Why punish them for the supposed benefit of of a tiny percentage? In what other case has that ever happened? Certainly not in the case of alcohol, tobacco and pharmaceuticals. These are the things that the articles should be talking about.

    Personally, it doesn’t bother me in the slightest that a few 12-15 year olds may get mental illness sooner. It’s just not that big a concern in the greater scheme of things. I am more concerned about them being warehoused in public schools where they can be victimized by the other students or killed in a shooting spree. Being in the average public school will drive a kid nuts a LOT sooner than smoking Cannabis. Better start banning all low-lifes from public schools now so they can’t harm the “vulnerable”.

    So somebody doesn’t supervise their 12-15 year old kids and they go nuts a few years earlier than they would have otherwise, big deal. If they had gotten their hands on some Prozac they would have gone on a killing spree many times more often than they would have otherwise or killed themselves. I don’t see anybody advocating the prohibition of Prozac or mandatory imprisonment for selling it.

  7. Anonymous on

    i tend to agree that smoking pot while young is not a good thing, especially when kids are often taking multiple substances at the same time or in the same period of life.
    and how do we keep young people from smoking tobacco and drinking alcohol?