July 26, 2007
Marijuana Users At Greater Risk Of Psychotic Problems

A meta-analysis of 35 longitudinal studies finds more schizophrenia and other psychotic illnesses among past and current users of reefer. (making the term "reefer madness" prophetic)

Cannabis users are 40% more likely than non-users to suffer a psychotic illness such as schizophrenia, say UK experts.

Writing in the Lancet, a team led by Dr Stanley Zammit from Bristol and Cardiff Universities said young people needed to be made aware of the dangers.

Beware the demon weed. Or as Mr. Mackey would say, "Mari-joowanna is bad, mmmkay?".

More frequent users had a higher incidence of problems.

Zammit and his colleagues combined data from 35 longitudinal trials, in which populations are observed over time. They found that, even after allowing for other factors, such as other substance use and intelligence, people who have taken cannabis are 41% more likely to develop schizophrenia or other psychotic problems than those who have never used it. Those who used cannabis most frequently were more than twice as likely to suffer problems.

It was less clear whether cannabis use was also linked to depression, suicidal thoughts or anxiety.

What I want to know: Are tokers fatter than the average person?

Share |      Randall Parker, 2007 July 26 11:56 PM  Brain Addiction

michael vassar said at July 27, 2007 4:42 AM:

Meta-analyses routinely show psychic phenomena to be real too. The reason is that if only a small fraction studies are strongly biased to reach a particular result but the typical study is neutral the result will typically show up in the meta-analysis via the law of large numbers.

Reality Czech said at July 27, 2007 11:32 AM:

Another question to ask:

is drug use (in general) self-medication for a pre-existing condition?  Just because someone is diagnosed for schizophrenia after having used cannabis, it does not mean that they were not attracted to the drug as a way of ameliorating the effects of the early disease.

Lono said at July 27, 2007 2:12 PM:


Really? Does this Really deserve to be posted on a "Science" blog??

(I was half joking to myself last night that you would be sure to post this study)

I mean - this could have easily be penned by Harry J. Anslinger himself.

In fact - the History channel last night was mocking a very similar study that Anslinger commisioned in the 30's that failed all peer review by real and objective scientists.

(Including the famous La Guardia commisioned study in New York.)

Please... Leave such nonsense on the Politcal Blog...


paranoia said at July 27, 2007 3:16 PM:

"Schizophrenia (from the Greek word σχιζοφρένεια, or schizophreneia, meaning "split mind") is a psychiatric diagnosis that describes a mental illness characterized by impairments in the perception or expression of reality, most commonly manifesting as auditory hallucinations, paranoid or bizarre delusions or disorganized speech and thinking in the context of significant social or occupational dysfunction. Onset of symptoms typically occurs in young adulthood,[1] with approximately 0.4–0.6%[2][3] of the population affected. Diagnosis is based on the patient's self-reported experiences and observed behavior. No laboratory test for schizophrenia exists."

This is from from Wikipedia.

So. Basically no one even knows what this is. No laboratory test exists!!!

More from Wikipedia -- "The disorder is primarily thought to affect cognition, but it also usually contributes to chronic problems with behavior and emotion. People diagnosed with schizophrenia are likely to be diagnosed with comorbid conditions, including clinical depression and anxiety disorders; the lifetime prevalence of substance abuse is typically around 40%."

So people with mild schizophrenia would almost certainly turn to alcohol, drugs or cannabis to alleviate some of these symptoms on there own.
And people from wealthier backgrounds would be getting doctor prescribed meds that I am sure have just as many side effects.

I suspect many of these "diagnosed problems" stem from living in an unnatural environment that they are not genetically adapted for.

We have evolved to be gatherer hunters, and farmers, to live in small communities that have deep relationships and emotional ties.

Living in modern dense cities, and confined to the "solitude in a crowd" that our modern society thrust us into is difficult for many people, even the ones that seem to function well in them.

Add the constraints of 9 to 5 jobs, and the many demands and restriction our society puts on us. Almost everything is locked up, food, water, money and jobs, shelter, companionship and even the ability for adequate rest is often denied.

These things are a difficult to adapt too, you would expect a bell curve where at the tails there are some that excel while others flounder.
For those who are floundering, add very aggressive law enforcement and a culture where people are more likely to call the cops rather then having a polite dialog and it's no wonder this group at the bottom of the bell curve suffer from paranoia, depression and anxiety disorders.

Our modern American (western) society is not at all friendly to those who can't play the game well.
So lets just call it some medical condition, let say label it Schizophrenia, Bipolar disorder, Asperger’s Syndrome take your pick, so we can write them off and lock them up.
While we are at it, lets outlaw anything that might help them cope that doesn't make a profit for the drug companies. This makes is all so much easier to justify locking them up.

These studies are junk science at it finest.

Fat Man said at July 27, 2007 10:38 PM:

"These studies are junk science at it finest."

Doctors with computers. Always a bad combination.

Gerald Hib bs said at July 28, 2007 7:55 AM:

"While we are at it, lets outlaw anything that might help them cope that doesn't make a profit for the drug companies."

The people who really get into marijuana have a genetic predisposition for addiction and often consider the drug something of a life saver as they deal with depression and other psychiatric problems. The downside is that marijuana quits working in 1-10 years and does indeed cause other problems on top of the condition for which they are self medicating. I am a Libertarian and all for freedom, especially for such a low grade drug as marijuana but let's not kid ourselves.

These people would be much better off with professional help combined with medication (either prescription or St John's Wort/Sam-e for depression.) To me this is a very difficult position because I see billions upon billions of dollars in lost potential each year, much less the human suffering, because our support systems for the mentally ill is so poor yet I oppose taxes and want more freedom. I guess I come down on the side of supplying free treatment and medication because while you are reducing suffering you are also getting the people treated to be much more productive which has a benefit for the economy which will then lead to more taxes on the ensuing economic activity.

So, while I think pot should be legal (as a moral position and because of the various costs associated with prohibition) I wouldn't recommend people actually use it especially those with the predisposition to get lost in it.

Lono said at July 28, 2007 9:36 AM:


As a former user (over a decade ago), and a Libertarian myself - I agree with you also - clearly the only recommended medicinal use of pot is for those with serious eye problems or severe nausea/pain caused by severe disease conditions.

It is not recommended to help alleive mental conditions - though I know it can sometimes temporarily do so - as my OCD goes nearly completely away while I am "under the influence" of it.

Clearly the best prescription for moderate mental issues is regular aerobic exercise and a healthy diet.

That being said, I find it abhorrent to try to manipulate scientific studies or statistics in order to attempt to justify social policy - which is exactly what is happening here with this latest UK study.

Doing so creates an atmosphere of distrust between scientists - and sows the seeds of public distrust in the scientific method - especially when these results go against common sense and the common citizens prsonal experience.

And leads to books like "The Secret" selling untold millions throughout the world.


Gerald Hib bs said at July 28, 2007 12:18 PM:

I agree that, most likely, this is junk science. I think the correlation is probably due to people self medicating rather than marijuana being causative. I was just responding to that single comment on MJ being a net positive for people with psychiatric problems. As to AIDS, cancer, etc -- get a vaporizer and have at it.

Tj Green said at July 29, 2007 4:51 PM:

If I had a family history of Schizophrenia,bipolar,psychopathy or dyslexia/schizotypal conditions (those with dyslexia are also schizotypal,and those who are schizotypal are also dyslexic,are we using two words to describe the same condition?),then I would avoid all mind altering substances.

Mr. E S I said at October 22, 2007 7:57 AM:

I'd say I have a short fuse - sometimes MJ helps, sometimes it makes things worse. I do believe bottling those emotional juices helps in the short term but the release can be a little more explosive. MJ helps 1 'bottle up'. Exercise / endorphines & crying really helped me after post-traumatic stress disorder but so did MJ. Alchohol fits its stereotype and amplifies moods, for me. When I was young (before I started smoking dope) I used to occasionally write an 'p' instead of a 'm' and sometimes vice-versa! Unusual mild dyslexia?! Hasn't happened for donkeys years! I think pot should be legal and also studied in an unbiased manner. The independent reports I've read show schizotypal traits precede, the biased, gov. reports say 'possible' cause. The effects of alcohol, IMO, are far more powerful than pot. Vaporizer, cakes and growing your own should be encouraged over buying from drug dealers and smoking with tobacco for previous users. It should at least be legal to grow a small quantity for personal use if over 18, IMO.

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