Study Debunks Claim That Pot Smoking Causes Mental Illness

  • by Paul Armentano, NORML Deputy Director July 1, 2009

    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.

    86 responses to “Study Debunks Claim That Pot Smoking Causes Mental Illness”

    1. How wonderful , now Mr. Brown can see the modern miracles of Science bashing his Idea to bits. Some times you have to admit you are wrong. I was wrong about thinking Ronald Regan was the driving force behind supporting the Contras in Nicaragua. I was also wrong thinking that the first President Bush should have gone into Bagdad. I thought that he stopped short of Victory. Now I know that he was wise not to go in there.
      So in the greater view of things. It is ok to be wrong , as long as we have a chance to accept our failings with grace and move on…. Soon we will be doing the right thing by the People.

    2. Jeremy R. says:

      Damn I wish I had this information prior to CNN’s week long topic on marijuana being I would have posted it to help the cause. Now we have this knowledge as well as other proof we need to keep up the fight to end this stupid prohibition on marijuana.

      I am sure NORML if in the future is faced with another debate if this is mentioned that NORML puts them prohibitionists in their place with the facts as NORML has and shall continue to due..

    3. […] the original here: Study Debunks Claim That Pot Smoking Causes Mental Illness Share and […]

    4. Spencer says:

      And, if you would like to add more, the Cannaboids found in Cannabis have shown to be extremely effective in treatment of many psychotic disorders. Schizophrenia is one of the many disorders that Cannabis helps treat and maintain those patients.

      So sad that our own government can’t give the time nor money to research further into Cannabis. Even published articles that have shown Cannabis has a huge potential in Medicine is overlooked by a bunch of old bastards who follow the rules from the 40s era and still dont know what an email is.

      We have young doctors, doing research, publishing articles, planning cannabis trials, who have shown the pros out weight the cons by miles, while are country is run by old, stubborn men, who aren’t up to date with any technology and are probably suffering from some elders disease (like alzhimers, which also is positively effected by cannabis use).

      The only reason were losing is because were a bunch of youngsters, living in a total youngster world, thats run by the elderly who say they “know better” and are trying to protect us.

      I know this is a long rant, but right know our country is in a crisis. The economy sucks, kids get into more trouble because of dealers who deal more then pot, people are suffering from thousands of disorders and diseases. The answer to all of this is simply LEGALIZE CANNABIS SATIVA AND CANNABIS INDICA. In an article, it was said that “cannabis will become Americas number one cash crop by 2015 if legalized by the year 2010”. Problems can be solved, our government just likes to create them.

      I believe I’m done and sorry if this is too much.

    5. David says:

      Well, DUH!!

    6. The American Psychiatric Association has for many years, classified marijuana users as a mental condition. Oh yes, your a mental case from the first toke of smoke or intake of eatable MJ treats, according to your psychiatrist schooling. I think it’s only fare that I give a reference here as we expect our opponents to do the same or they’re considered full of sh** as usual. My next comment below will display a link to this information.

    7. http://www.revver.com/video/514098/smoking-marijuana-mental-disorder-psychology-with-sandy/

      Mental Disorder #292.89 as listed by the American Psychiatric Association, is the reference for you that I’ve mentioned in comment #5 above, the marijuana user’s classification. The above link will take you to a video featuring a very nice lady, “Sandy,” who will explain everything. The bottom line here in the video is that you’ve been classified for a long time as a mental case if you use marijuana. Well hell, put us all in the same room and watch us be happy. Shit, who the hell wants to be sad, depressed, etc., when we can enjoy cannabis for the reason it was put upon the face of the earth for! God thought of everything when he made this place we call earth.


    8. Manford Mantis says:

      Two things…and…”that’s that”

      1. Liars are liars…no matter where they are on the planet.

      2. The Data Quality Act…and…the President’s Memo to Executive Heads of Departments and Agencies.

      If We the People don’t enforce number 2…it’s our own damned fault…and…We should shut up!

    9. […] post: Study Debunks Claim That Pot Smoking Causes Mental Illness Share and […]

    10. Joel: The other Joel says:

      Prohibitionist are trying very hard, but in some cases it doesn’t matter. They still got money and support. Where did all that money go?