Study Debunks Claim That Pot Smoking Causes Mental Illness

Much has made — by the mainstream media and others — of the claim that cannabis use causes certain types of mental illness, specifically schizophrenia and psychosis.

Most notably perhaps, a team of researchers writing in the July 28, 2007 edition of the prestigious scientific journal The Lancet, boldly proclaimed that smoking cannabis could boost one’s risk of a psychotic episode by 40 percent or more.

Naturally, this alarmist rhetoric received wall-to-wall coverage by the mainstream press. Even more troubling, the supposed ‘pot-and-schizophrenia’ link was one of the primary reasons cited by British PM Gordon Brown, ex-Home Secretary Jacqui Smith and others as the impetus for reclassifying cannabis (from a verbal warning to a criminal offense punishable by up to five years in jail) in the United Kingdom.

Of course, there was a fatal flaw with The Lancet’s argument — one that, oddly enough, every single MSM outlet failed to mention. Empirical data did not support the investigators’ hypothesis that smoking marijuana was associated with increased rates of schizophrenia or other mental illnesses among the general public — a fact that even the authors begrudgingly admitted when they declared, “Projected trends for schizophrenia incidence have not paralleled trends in cannabis use over time.”

Which brings us to 2009.

Two years after The Lancet’s dire predictions, a team of researchers at the Keele University Medical School have once and for all put the ‘pot-and-mental illness’ claims to the test. Writing in a forthcoming edition of the scientific journal Schizophrenia Research, they compare long-term trends in marijuana use and incidences of schizophrenia and/or psychoses in the United Kingdom. And what do they find?

“[T]he expected rise in diagnoses of schizophrenia and psychoses did not occur over a 10 year period. This study does not therefore support the specific causal link between cannabis use and incidence of psychotic disorders. … This concurs with other reports indicating that increases in population cannabis use have not been followed by increases in psychotic incidence.”

Should we expect an apology — or even better, a change in policy — from the Gordon Brown regime any time soon? Or at the very least, will some sort of ‘correction’ be forthcoming from the mainstream news media?

I wouldn’t hold my breath.

– Article from NORML.



  1. Anonymous on

    if water was illegal to drink, many more would become psychotic too.

  2. Sir Les on

    Yes What Causes the mental conditions??

    Here is what I have found to be true.

    Because they outlaw and make it illegal to use/grow/posses…in that the user… has to lie, or become two faced to live in society in these democracies….which are imposing this illgotten Law, made up with lies!

    The lies used to remove the plant from the trade tables of the world, is now backfiring on the ones who promote this ideal….they even are making wars over it in Afghanistan…and with in their bent systems…
    Poor food crops, drought, odd weather, pollution from fossil fuels…and virus and bacteria are running a muck…healthcare is going up…and costing trillions to solve for by the bent pharmacuticals they produce…to replace Marijuana and other plants they deliberately remove which are benefical for our health care of the world.
    All because of the liar and the lies.

    Now if we have to lie to do what we know we love to do..we become two faced…dual personalities are developed by the lie…and the lies become part of us….and so we create lies to do what we want to do naturally, because of the bent laws imposed.
    And we lie because of the bent law…so we can continue to do what we love to do….which is not a broken law of God…infact God says it is all good!

    So someone is not listening to GOD’S word and will.
    And they are changing God’s word, and will to a detramental, which causes woe and wrath to come down from heaven.

    So it is not Marijuana that causes mental issues…it is the liar, and the lies they tell to make us/paint us criminals for doing what come as a natural outlet for religious meditation…a means to calm down,relax, and enjoy life…becomes a paranoid and stressful experience trying to hide from the public scurtany and policed society..

    And the lies do not stop with Marijuana in these bent democracies…lies are all around…Free trade?
    Liberty and freedom for ALL?
    In God we trust?

    Yah just a few of the bigger lies they spew out of their mouth peices…..

    So why is it these societies humans make, believe in the lies they tell?…to cause mental illness?

    That is still a enigma!

    Sir Les

  3. Anonymous on


    yes – it is a fairly common practice for politicians and police / prosecutors to phone the doctor and order them to assign a medical diagnosis to a pot head – you will also be labelled a drug addict – but the most common reason for the police/courts to request a medical psych test – is so that they can introduce hearsay evidence ( they call it collateral information ) into your court / police files.
    I would suggest this is the main reason.
    Doctors are allowed to use hearsay as “real evidence”.
    And of course you also have to factor in the straight out fabrication of evidence by criminals in the medical field.
    The Doctors here have a history of being executed for this behaviour. o

  4. Covey WhiteGold on

    Since my studying and understanding of the Endocannabinoid system I have to say that I agree the alarmist claims is wrong in the sense that it leads to any kind of mental disorder but what it could be is the fact that I was reading their Endocannabinoid system is hindered in schizophrenic patients by producing less in the system and when they smoke cannabis it helps some and others it pushes them over the edge because of their less producing Endocannabinoid system.
    That’s where the controversy comes from and with medications made now they can block the cannabinoids if necessary or increase if that’s the case in each patient being different.

  5. Anonymous on

    I would like to see a 10 point (or more) list of the myth’s associated with Cannabis use, and the reason that they are myth’s printed side by side.
    Then that list should be sent to every political party in the world – then make sure all the media prints a copy of it.
    Did you see this information any where else other than a NORML link ?? I know our paper didn’t print it like they did the link to mental illness.
    The information is out there – We know it but “We” don’t seem to be in charge any more – time to educate our “Leaders”, especially here in Canada, that the path they have chosen is just plain wrong.

  6. George Lenard on

    use the power of their authority to makes such claims against the moderate use of a substance that in Canada has been excepted by Harper as and I quote, ” enhances the quality of life”? Or how is it we have medical exemptions?