Thursday, July 26, 2007

Up In Smoke?

A British study that shows a link between marijuana use and psychotic behavior, is a setback for those arguing for legalization. The study found the following:
The new review suggests that even infrequent use could raise the small but real risk of this serious mental illness by 40 per cent.

The scientists found a more disturbing outlook for "heavy users" of pot, those who used it daily or weekly: Their risk for psychosis jumped to a range of 50 per cent to 200 per cent.

"We've reached the end of the road with these kinds of studies," said Dr. Robin Murray of King's College, who had no role in the Lancet study. "Experts are now agreed on the connection between cannabis and psychoses. What we need now is for 14-year-olds to know it."

There was one curious admission by the researchers, akin to the "gateway drug" argument:
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.

Nothing new, in that other studies have shown that marijuana users are statistically more likely to use other drugs. I've never bought into the argument that marijuana use translates into a path to "harder" drugs, because you could just as easily conclude that those that drink are more like to try pot, than non-drinkers. Is booze a gateway drug?

My point, as it relates to this study. Is it not inherently problematic to conclude that marijuana is the cause of increased psychosis, when your sample group is contaminated? The researchers obviously found marijuana users had a higher "tendency" to be users of other drugs, which undercuts an isolation of marijuana as root cause. You have a cocktail of potential culprits, which should serve as a red flag, in drawing any definitive conclusions. If the study limited itself to people that had only used marijuana, you still have the obvious environmental problems, but the case is far more persuasive. It is akin to studying the effects of steroids, with some of the patients also taking growth hormones. A small "skunky" smell with the sample group, which might detract from "we've reached the end of the road with these kinds of studies" proclamations.


Anonymous said...

Jaysus wepput.

"Unmask", "pre-existing", and "Several authors reported being paid to attend drug company-sponsored meetings related to marijuana, and one received consulting fees from companies that make antipsychotic medications."

Soon we'll be told sugar is good for us and drizzling crude oil on our veggies isn't a risk.

Steve V said...

Kraft light sweet crude? Half the calories?

Eric said...

Interesting, like many studies it is important to read the fine print.

Although I personally wouldn't doubt the veracity of this study that's more because it fits with my own opinion. But again, its important in reading studies to set aside your own personal opinions and view things from a pragmatic, does-the-methodology-make-sense sort of view.

Its like studies which showed that drinking a glass of wine a day would reduce heart disease. The studies didn't mention that the same effect can be obtained by drinking a glass of grape juice a day. (without any of the liver disease problems)

I'm curious if they had trouble finding a group of people who only did marijuana and none of the harder drugs?

Anonymous said...

Pretty suspect study. No causality shown, etc.. what dana said.

It's the scientific study equivalent of schwag.


Tomm said...


What are your guests smokin?

Not that I've ever tried "the marijuana". But I've heard that it can make you a little paranoid. Not that I would know personally...

Give us all a break. The results of this study are perfectly in line with the effects of longterm use.

Potheads being psychotic?

Who would have thought!


That being said, there is room for a little attitude adjustment now and then.


Anonymous said...

Ah yes, Tomm, welcome to Reefer Madness Version 2.0.

All those 'psychotic' potheads killing and maiming people. Not.

It's a bogus conclusion based on a flawed methodology. It's laughable.

Now having said that I'm going to light up. Just because it's almost bedtime. How psychotic of me.

Tomm said...

frank frink,

Hear that knock? I think its the cops...

That clicking you hear on the phone? ...its just clicking.

No man, nobody can tell your stoned, with those glasses on your eyes don't even show.

I sure could tie into a big bag of dorito's and a big gulp.

What's the most common word used by Frink Frank?


But I'm really feeling mellow right now. Don't want to maim anybody. Why can't we all just get along!


Koby said...

>>>> “Not that I've ever tried "the marijuana". But I've heard that it can make you a little paranoid. Not that I would know personally...”

Exactly. This has lead Mitch Earleywine, a professor of psychology at the University of Southern California, to criticize the methodology of one prominent study referred to tonight in the CBC’s the National.

“Mr. Earleywine notes that Mr. Fergusson and his colleagues did not actually diagnose psychosis in the marijuana smokers they studied. Instead, they administered a short mental health questionnaire that asked if the respondent had ever experienced any of 10 "psychotic symptoms."
Some symptoms are clearly troubling, such as "hearing voices that other people do not hear" and having "the idea that someone else can control your thoughts." Others are not so obviously strange: feeling that other people cannot be trusted; feeling that you are being watched or talked about by others; never feeling close to a person; and having ideas and beliefs that others do not share.
Among 25-year-olds who had never smoked marijuana, the mean number of symptoms reported was 0.64. That number rose among those who smoked marijuana: Less-than-monthly users reported 0.89 symptoms, while daily marijuana smokers reported 1.95 symptoms. That rise, modest though it may be, is statistically significant.
But Mr. Earleywine believes there might be less here than meets the eye. In a letter to be published in the journal that published the study, Mr. Earleywine notes that it is fairly common for marijuana intoxication to cause feelings of paranoia, but the researchers "give no indication that respondents were asked to distinguish between feelings experienced while intoxicated and feelings experienced at other times. Thus, we are left with no clue as to whether these are long-term effects actually indicative of mental illness or simply the normal, passing effects of acute intoxication."

A significant drawback in this body of literature is that there are no epidemiological studies to support what is being asserted. Despite jump in marijuana use, there simply is no jump in the number of people being diagnosed with schizophrenia.

This has led some to argue that the cart is being put before the hoarse and not the other way around. Rates of alcoholism and drug abuse of all kinds are much much higher in the schizophrenic population then in the general population and no one is inserting, for example that alcohol abuse leads schizophrenia, indeed quite the opposite. The following should given you an idea of the magnitude of the problem. “The Epidemiologic Catchment Area (ECA) study2 (2 The ECA study was a nationwide survey that used DSM–IV criteria to determine the prevalence of psychiatric disorders in the general population and among people in treatment.) found that 33.7 percent of people with a diagnosis of schizophrenia or schizophreniform disorder (a related disorder marked by the same symptoms as schizophrenia but lasting less than 6 months) also met the criteria for an AUD diagnosis at some time during their lives and that 47 percent met the criteria for any substance use disorder (excluding nicotine dependence) (Regier et al. 1990). Rates of substance use disorder tend to be higher among males and among people of both genders and all ages in institutional settings, such as hospitals, emergency rooms, jails, and homeless shelters. This holds true for people with and without schizophrenia (Regier et al. 1990).”

Anonymous said...

Of all the people I know who have used marijuana - NONE have any mental problems.

I would guess, if one exists, alcohol does the same thing and yet it's legal.

Scotian said...

Correlation is not causation. That is my response to what I read regarding how this study was done. The way this is being reported versus what it actually says though makes it seem that there is such a causality link when clearly no such link can be drawn by the study author's own words. Of course the American anti-drug crusaders are going to think it is persuasive, but that is true for anything which sounds like it aids their arguments no matter how poorly they do so. This study is a joke.

To make such a clear case what they needed to do was get a study group that only used marijuana for a period of several years and a control group which did not (nor used other drugs like alcohol, otherwise you are introducing too many different variables within the control group as to render it useless for it's purpose) and then see what kinds of results show up. This though was a farce, and to be honest I am a little saddened to find out that the Lancet published this pos of a study from which no solid conclusions other than flawed methodology can be taken.

Chalk another one up for Reefer Madness 2.0 indeed...

canuckistanian said...

damn you scotian! here i was scrolling through the comments just waiting to pounce with the classic "correlation is not causation", and you go and ruin it for me right at the end ;-).

this study looks quite shoddy, and the causal connections could plausibly be going any number of directions. that said, this is nonethelss a good thing (hopefully...silver lining and all), as it may lead to more research in this area that has not been researched nearly enough, obviously.

amazing, the impression one would have reading the headline as opposed to the results.

Anonymous said...

koby, You pretty much nailed it.

You too, scotian.

Anon at 9:57pm.
I found it quite interesting that the study makes claims of marijuana users also being users of other drugs. I have no doubt that is likely true certain susbsets of the overall pot smoking population. From my own anecdotal experience the only other drug that my pot smoking friends and acquaintances consume is the occasional beer or three. In the comfort of their own homes.

Anonymous said...


That's too funny. Doritos and a big gulp.

That would be the day I slit my wrists. (I don't eat 'snack' foods such as chips or drink carbonated sugar waters).

But, I guess stereotypes are hard to shake off.

Speaking of stereotypes, what sort of music would you think I was listening to last night? As a 'stoner' stereotype I mean. ;-)

Steve V said...


I have a strong feeling.

Koby said...

Salon has a good article covering most of the issues here and then some.

a Sample

“Perhaps the strongest piece of evidence to cast doubt on a causal connection between marijuana and schizophrenia is a long flat-line trend in the disease. While marijuana use rose from virtually nil in the 1940s and '50s to a peak period of use in 1979 -- when some 60 percent of high school seniors had tried it -- schizophrenia rates remained virtually constant over those decades. The same remains true today: One percent or fewer people have schizophrenia, a rate consistent among populations around the world. This is in stark contrast to studies linking tobacco smoking with lung cancer, where rises in tobacco use were accompanied by rising rates of lung cancer."

I have addressed some of the same issues in my blog on Margret Kopala

Anonymous said...

Thanks Steve!

Chuckling. I think I just had a flashback.

Careful With That Axe, Eugene.