Diagnosis: Reefer Madness

A meta-analysis of 32 studies in the July 28 issue of The Lancet finds that pot smoking is associated with a 41 percent increase in the risk of "any psychotic outcome." According to the Daily Mail, this means "smoking just one cannabis joint raises danger of mental illness by 40%." A.P. is slightly more cautious, reporting that "using marijuana seems to increase the chance of becoming psychotic." Time ran the A.P. story under the headline "Marijuana 'Raises Psychosis Risk.'" A.P. introduces a pretty important note of caution in the fifth paragraph:

The researchers said they couldn't prove that marijuana use itself increases the risk of psychosis, a category of several disorders with schizophrenia being the most commonly known.

There could be something else about marijuana users, "like their tendency to use other drugs or certain personality traits, that could be causing the psychoses," Zammit said.

By contrast, the Daily Mail waits until the 29th (and last) paragraph to note that "others questioned the link, pointing out there has been little change in rates of schizophrenia in recent years despite the rise in cannabis use and the increasing strength of the drug." But the paper more than makes up for that concession with a sidebar on "three heavy drug users and their horrific killings" that Harry Anslinger would have envied. The best of the three:

Son of a nurse at Broadmoor Thomas Palmer butchered two of his friends during a woodland walk after his mind was warped by smoking skunk—a particularly potent form of cannabis.

Then aged 18, he virtually beheaded 16-year-old Steven Bayliss and repeatedly stabbed Nuttawut Nadauld, 14, near their homes in Wokingham, Berkshire in September 2005.

Palmer had started using the drug at 14. He told doctors he had not been smoking on the day of the killings but admitted to using skunk regularly in the weeks before the brutal attack.

Scientifically, correlational studies like those analyzed in the Lancet article are superior to such gory anecdotes, but they cannot answer the crucial question of why marijuana users are somewhat more likely to be diagnosed as psychotics. As the authors note, "The uncertainty about whether cannabis causes psychosis is unlikely to be resolved by further longitudinal studies such as those reviewed here." By the same token, we can't say for sure that marijuana doesn't trigger or exacerbate psychological problems in certain vulnerable individuals. But as Lester Grinspoon and James Bakalar pointed out in connection with psychedelics, the same could be said of any emotionally powerful experience.

Furthermore, the risk is much lower than the impressive-looking 40 percent figure suggests. The overall incidence of schizophrenia, A.P. says, is "less than 1 percent," in which case smoking pot would raise it to less than 1.4 percent. That's assuming the relationship is causal, which it might not be, and that the risk is random, which it almost certainly isn't.

Addendum: Alex Duncan points out that reason contributor Maia Szalavitz has a post on the study at the STATS site, emphasizing the lack of a correlation between marijuana use rates and the incidence of schizophrenia.

[Thanks to Dan Greene and jimmydageek for the tip.]

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  • thoreau||

    Although I was skeptical of the report, I made the mistake of not putting any of that skepticism into my blog post about this a couple days ago. I just made a few jokes about Cheetohs and a lawsuit against pot dealers titled "The US vs. This One Dude (he's cool)."

    The commenters at Unqualified Offerings were merciless.

    Anyway, good analysis Jacob. Nobody trashes the junk science like Jacob Sullum.

  • Bubba Zanetti||

    The obvious correlation between (any) drug use and mental illness is self-medication, i.e., undiagnosed people often use drugs/alcohol for relief from the symptoms of mental illness.

  • ||

    How long before there is a hydro strain called Schizo?

    BTW the Drug Czar is in Dallas today to look into our cheese "epidemic." Looks like the old. give a drug a new name to get more drug war dollars, ploy works again.

    Can't wait to see the shiny new APC.

  • ||

    Dammit Zanetti, you beat me to it. Whoever wrote that pot raises the danger of psychotic episodes should be laughed at. And when we laugh at these idiots, hopefully we'll accidentally spit some Cheetohs.

  • ||

    skunk-a particularly potent form of cannabis...

    In Bizarro world.

  • ||

    So 50 is the new 20, and correlation is the new causation. Rock.

  • ||

    Time ran the A.P. story under the headline "Marijuana 'Raises Psychosis Risk.'"

    Here's an alternative headline that is at least as likely to be true:

    "People at Risk for Psychosis More Likely To Use Marijuana"

    Duh.

    I wonder how other socially rebellious behaviors correlate with later psychoses. High alcohol use? Dropping out of school? Getting fired from work? Drag racing? Watching Fox News?

  • D. Greene||

    I sent this link in hoping it would get written about here and my hopes were answered.

    Oh, and I commented on that Daily Mail article on their website, and their comments go through an approval queue. I said in effect that this was irresponsible scaremongering, so naturally it was not published. Last I checked only one comment has been approved, even though theier article was linked on drudge and I'm sure thousands commented.

  • crap-action-jackson||

    dumb question here:

    Is it possible that a study like this is skewed by the (possible) fact that people are more likely to be diagnosed as having mental problems if they use drugs, by simple means of getting caught up in enforcement, interventions, etc: situations where the "mental" behavior is red-flagged because of the drug use? I guess this is a way of asking - how do these studies identify who is nuts? Did they take a report from the subjects themselves, or start with groups of undiagnosed people and do their own direct diagnoses? That make any sense?

  • ||

    skunk - a particularly potent smelling form of cannabis.

    Could be a local jargon thing. Where I'm from Skunk fell into the mid-grade category of smoke along with Crippies. Not quite kind, but better than Mex.

    Maybe to the Brits, anything strong and stinky falls under the blanket term of skunk.

  • ||

    I'm left wondering why someone writes this sort of story in the first place. Correlation is not causation, which the article and the studies make fairly clear. So we're left with a collective "huh, that's sorta interesting" kind of piece.

    Silly. Good analysis here though.

  • crap-action-jackson||

    Unless these studies did their own blind diagnoses, then I wonder: how/why did the diagnoses come to be made in the first place? Did the fact of the illegal drug use prompt the effort for a diagnoses?

  • ||

    Maybe to the Brits, anything strong and stinky falls under the blanket term of skunk.


    Or "good cheese".

  • ||

    I take it that this would be the same Lancet that wrote that crap study estimating that the war had killed 100,000 people in Iraq by 2004 (a number they came to by averaging the difference between 8,000 deaths and 194,000 deaths)? Hardly surprising that their study on pot is also full of questionable numbers with shady causal links.

  • UCrawford||

    Here's Fred Kaplan's debunking of the Lancet's Iraq study:

    http://slate.com/id/2108887/

    I'm sure that if some enterprising journalist out there wanted to dig he or she could probably find similar errors in this newer study.

  • ||

    But wait, there's more:

    "A single joint of marijuana obstructs the flow of air as much as smoking up to five tobacco cigarettes, but long-term pot use does not increase the risk of developing emphysema, new research suggests."

  • Jennifer||

    Pot smokers are 538.7 percent more likely than non-pot-smokers to suffer from the psychotic delusion that the government's lying when it talks about how super-dangerous pot smoking is.

  • ||

    "Hardly surprising that their study on pot is also full of questionable numbers with shady causal links."

    I agree. Once a published study is debunked, the disgraced publication should close up shop, execute its staffers and f*ck itself in the face.

  • ||

    But as Lester Grinspoon and James Bakalar pointed out in connection with psychedelics, the same could be said of any emotionally powerful experience.



    This goes a long ways towards explaining 9/11 Truthers. They witness a horrific event on television, a powerful emotional experience, and subsequently lose all touch with reality. No pot is needed, just a willingness to believe shit. Heck, just yesterday I came across a truther site claiming that an energy beam from Star Wars military satellites did it, complete with reams of "evidence". If I were of a more conspiratorial bent, I would say 9/11 was a plot by Big Psycho-Pharma to sell more Thorazine and Ritalin, instead of the plot it really was by kooky radio personalities to boost their ratings.

  • ed||

    One might assume from the comments above that pot has no psychoactive properties whatsoever.

  • ||

    Despite the lack of a causal relationship and other unscientific conclusions, we can expect to have this 'study' thrown in our faces by the ant-marijuana forces for years to come whenever we try to engage in a logical discusion about ending prohibition.

    Aw.....shit.

  • Jane||

    If more psychotics use MJ than non-psychotics, that pretty much proves that the MJ causes psychosis. This was well known as long ago as the 1930's which is why it was initially banned. It is good to see evidence for why the ban must stay in place, if people used MJ they would become psychotic, so we need the law because it effectivly prevents nearly all drug use.

  • Sal Paradise||

    "smoking just one cannabis joint raises danger of mental illness by 40%."

    That may be, but it also increases the listening enjoyment of Dark Side Of The Moon by 40%.

  • ||

    I'm of two minds on this topic.

  • ||

    I don't wanna work
    I just wanna rail on teh trolls all day

  • ||

    Jane: you ever play those video games, like golf, where there is a power bar that rises to the top of a meter, and the idea is to hit the button right when the power is at the top, but if you wait one second too long, all your power disappears and you get a wimpy shot? Your post is the troll version of that.

  • ||

    "smoking just one cannabis joint raises danger of mental illness by 40%."

    I was just making a comment on another thread about how ignorance of statistics leads to people believing bullshit.

    This sounds like the studies that came out in Great Briton a couple of years ago that pulled the rug out from an effort to legalize pot. The whole thing is just the same old overblown hysteria of a few data points at the edge of resolution. I seriously doubt that smoking pot causes mental illness. I suspect the pot smoking might be triggering psychotic episodes in people already ill.

    I have my one word answer to every argument against legalization - Alcohol. I'd be very interested to know how much booze "raises danger of mental illness".

  • ||

    Jane must have smoked more than the rest of us combined. She acts like a troll to get attention.

  • poco||

    Jane, your ideas are intriguing to me, and I wish to subscribe to your newsletter.

  • fyodor||

    Ah, so THAT'S what did it to me! And me. And me. And me. And me....

  • Paul||

    "smoking just one cannabis joint raises danger of mental illness by 40%."

    Why would we be surprised that anti-marijuana statistics would be any less breathlessly hysterical than cigarette smoking statistics? And how long is Reason going to continue to see these areas of prohibition as separate issues?

  • ||

    According to their philosophy I should have been a drooling headcase about 5000 doobies ago.

    I love the way they always highlight a few obscure instances of someone that smoked pot at some point in time and then went on later in life or even while buzzed to commit murders as psychotics. Did any of those criminals also drink Budweiser and if so how can we be sure that was not the cause of their murdering ways. What about breast milk perhaps there is a link as well between them on that consumption habit.

    With such a large pool of people using drugs recreationally how hard is it to find 5 or 10 that are lunatic murders and would be no different no matter what. I bet we could find the same percentages of murderers based on professions as well. If the number in the pool is large enough you will always have some within it that do these things regardless of the type of pool being researched. Its like saying getting a law degree leads to psychosis since these 5 lawyers over here killed people. Once again lets blame something other than the person who commited the crime. After all had they not smoked the plant they would be just fine and normal adults right now and we would all live in a healthy mental world without any wackos, right.

    FWIW- I read yesterday about the "latest," in drug epidemics amoung the youth. The all new and never before heard of huffing of Freon. This is old news to anyone other than the reporter obviously and if its the next thing that will destroy our youth and country. I have to ask why it failed to do so 20 years ago when it was new for the 1st time? They are beginning to recycle epidemics now as if they are all new.

  • ||

    Wouldn't a twin study be a pretty easy way to do a longitudinal study on this? Find out the correlation of psychosis between identical twins where both smoke and/or where both don't smoke. Then do the same with ones where one smokes and doesn't. Those results would mean a lot more to me.

  • ||

    ....now what did I come in here for....?

  • ktc2||

    Are there people out there who have really never smoked pot? I mean realy, not lying about it like the entire government, police force, evangelists, etc.

  • Randolph Carter||

    yeah, there are tons of people who've never smoked pot. There's a built-in bias from weed-smokers because most of them hang out with other people who smoke.

  • ||

    Are there people out there who have really never smoked pot?

    People, yes. Cool people, no.

  • Tym||

    I love the way they always highlight a few obscure instances of someone that smoked pot at some point in time and then went on later in life or even while buzzed to commit murders as psychotics.

    Maybe these few people are basically PSYCHOTIC regardless of what substances they use; nad as someone said, any real corelation may likely be self medication.

    Did any of those criminals also drink Budweiser and if so how can we be sure that was not the cause of their murdering ways.

    Alcohol is one of the few drugs that is actually corelated with violent antisocial behaviour. Kind of stupid that it is the one legal drug.

  • ||

    I would never consider trying pot, tho' a dorm mate once invited me to join her & some friends to smoke it -- as if they were getting together over a pizza. Only someone who is already a bit "off" mentally would use illegal drugs, if only because of the illegal aspect.

  • ||

    Only someone who is already a bit "off" mentally would use illegal drugs, if only because of the illegal aspect.

    Like I said. Cool people.

  • ||

    What about the correlation/causal relationship between being both Catholic and pedophilic? Most studies' outcomes are predicated on who is funding them and for what purpose. As I see it, the main problem is that pot smokers haven't gotten it together enough to fund their own studies.

  • sean||

    snootches nooga muthafuckin noog!

    Nice little bit of FUD.

  • ||

    I'm actually quite interested in true psychosis-- i.e., schizophrenia, and related designations--and have been reading a number of personal case studies about it recently. The problem is that science really still doesn't know what causes it. There are some indications that diet and nutrition can also be a factor in triggering outbreaks, but the bottom line is that some people are just much more susceptible to it than others. Probably genetic.

    The alleged marijuana connection is old news. I personally think that, yeah, there's probably some slight truth to it. People that are already at high risk of psychosis should not smoke lots and lots of pot. Wowee. But it's hardly going to cause a change in any significant number of people that are not already predisposed to it. As Jacob mentions, the 1% versus 1.4% statistical odds. This is just scaremongering by the drug warriors.

    One of the most widely touted personal accounts of schizophrenia is The Eden Express by Mark Vonnegut (which I recently read, and frankly, didn't think that enlightening about the descent into madness). Vonnegut (Kurt's son) of course smoked lots of pot as a hippy commune farmer during the 70's. But I was much more interested by E. Thelmar's The Maniac written during the 20's, and am currently reading the famous account of Daniel Schreber, Memoirs of My Nervous Illness from the turn of the century. I highly doubt that either Thelmar or Schreber were puffin' much skunkweed.

    If anyone would like to read a great account of what schizophrenia's like I recommend Operators and Things, by Barbara O'Brien (a pseudonym). Written in the 1950s, she drops into complete paranoid schizophrenia for a period of about six months and then spontaneously recovers. The book is out of print, but you can find a copy through a library search.

  • Freelance Editor||

    Let me fix this for you:

    I would never consider trying pot have a closed mind, tho' a dorm mate once invited me to join her & some friends to smoke it -- as if they were getting together over a pizza to relax and enjoy themselves. Only someone who is already a bit "off" mentally would use illegal drugs think that the gov't knows what's best for us, if only because of the illegal aspect fact that they are consistently not acting in our best interests.

    Well, it's not perfect, but considering what I had to work with...

  • ||

    Just a small bit of anecdotal evidence for the "reefer madness" theory:

    Both the current President and his predecessor have admitted trying it.

  • ||

    Only someone who is already a bit "off" mentally would use illegal drugs, if only because of the illegal aspect.

    Yes, because blindly obeying all laws is such a sign of mental health.

  • ||

    JS does a better than average job analyzing the numbers here. The rest of the thread demonstrates a pretty poor grasp of the underlying claims.

    Correlation does not equal causation.
    Correlation does, however, mean something.

    These numbers indicate something about the relationship between MJ and psychosis/Mental Illness. Interpreting that requires a careful reading of the studies.

    If done correctly, a meta-analysis of well designed studies is a good source of evidence.

    Even if causal, the relationship btw MJ and MI would not in any way support the current policies regarding the drug. It informs, rather, treatment for those with MI or a desire to quit smoking MJ. It also provides a basis for a risk analysis by those who enjoy MJ.

  • SIV||

    The problem is that science really still doesn't know what causes it.

    Despite having various explanations that go in and out of fashion. You might try....

    HERE

  • poco||

    a dorm mate once invited me to join her & some friends to smoke it -- as if they were getting together over a pizza.

    I bet there was pizza involved later...

    Mmm, pot + pizza. That's the whole point of college! Isn't it? SOW, I can attest that there's at least one valid reason not to smoke (too much) ganja: munchies can be fattening. Yet not as fattening as the atypical antipsychotics like Zyprexa that shrinks press upon schizophrenics.

  • ||

    Sure there are people who have never tried pot. I'm one of them. Lots of reasons why. Firstly, I don't much care for inhaling smoke from anything. Makes me cough and wheeze. Secondly, it's illegal, which means that a certain amount of danger, risk, and (justified) paranoia go along with pot use. Most of all, though, I decided that all the good things people experience while smoking pot--- being goofy, silly, relaxed, social/friendly, enjoying music, etc.--- could be mine while sober. Stoners don't have a monopoly on all that fun stuff they get to do and experience. I can be (and am) just as goofy, just as relaxed and social, and listen to music just as deeply and intently as the most ardent pot user. And I get the side benefits of remembering conversations, not believing that nonsensical conversation is actually profound in some way, or (the big one) not risking arrest.

    Finally, I believe that the more one smokes pot, the more one wants to associate more-or-less exclusively with other pot-smokers. Kind of limits one's friends in a way I wouldn't care to do. I'm a musician myself, and I know and am friends with lots of people who use pot. None of them are psychotic in any way. But as a group, they do tend to have more problems with the law in general--- usually not pot-related offenses, either--- than non-users. None of them have yet convinced me that I would be better off if I tried using pot. The way things are now, I get to have all the fun that pot smokers have, yet experience none of the drawbacks. If that makes me "not cool" in some way, sorry. But the fact is, I have just as much fun sober as pot-users do while stoned, and afterwards I can remember the good times better than they can.

  • ||

    I get to have all the fun that pot smokers have, yet experience none of the drawbacks.

    One could argue that pot smokers have more fun than you because they get to have all the fun you have, without the drawback of not being high.

  • ||

    You can be cool and not smoke pot.

    But, it be a lot cooler if you did.

    Yes indeed.

  • ||

    Finally, I believe that the more one smokes pot, the more one wants to associate more-or-less exclusively with other pot-smokers.

    This is based on your limited experiences. Based on my limited experiences, it's not the case at all.

    But the fact is, I have just as much fun sober as pot-users do while stoned, and afterwards I can remember the good times better than they can.

    Marijuana isn't like alcohol, in that you don't black out. Pot smokers (especially folks who use pot exclusively) generally have no problems remembering what they did when they were high.

  • ||

    I'm waiting for the report that the brdge collapse im Minneapolis was caused by people smoking cannabis.

  • ||

    brdge=bridge

  • ||

    brdge=bridge

    I think I see the beginning of an explanation right there.

  • brian||

    Then aged 18, he virtually beheaded 16-year-old Steven Bayliss and repeatedly stabbed Nuttawut Nadauld, 14, near their homes in Wokingham, Berkshire in September 2005.


    How do you "virtually behead" someone? I really don't understand.

  • ||

    SIV

    Despite having various explanations that go in and out of fashion. You might try....

    HERE


    Aye carumba!

    You are posting on the wrong thread.
    The "look how wacky Scientology is" thread is down further...

  • me||

    How do you "virtually behead" someone? I really don't understand.
    Nearly Headless Nick, duh

  • Another Phil||

    munchies can be fattening. Yet not as fattening as the atypical antipsychotics like Zyprexa that shrinks press upon schizophrenics.

    True about the Zyprexa weight gain. Zyprexa is a great antipsychotic medication though. Taking Metformin (aka Glucophage) at the same time as Zyprexa helps prevent most of the weight gain for a lot of people (myself included). It seems to be most effective if you start taking the Metformin when you start taking the Zyprexa; it's not so effective if you start it after you've already gained the weight. Also, weight gain is associated with the other atypical antipsychotics also (with the exception of Geodon), although not as dramatically as with Zyprexa. Also, although marijuana may not make you psychotic, but it doesn't help you if you are: Zyprexa can.

    To be fair, Zyprexa comes with other risks too: an increased risk of diabetes and the risk of tardive dyskenisia (involuntary twitches that don't go away after you stop taking the medication). Metformin may lower the risk of diabetes though. It definitely sucks to have to weigh these risks against the benefit of not being schizophrenic anymore, but such is the current state of pharmacological science.

  • ||

    zyprexa risks are to high may work but it also kills you thats why eli lilly started pushing diabetes meds

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