Marijuana may increase psychosis risk

[Bond]

Using marijuana seems to increase the chance of becoming psychotic, researchers report in an analysis of past research that reignites the issue of whether pot is dangerous.

The new review suggests that even infrequent use could raise the small but real risk of this serious mental illness by 40 percent.

Doctors have long suspected a connection and say the latest findings underline the need to highlight marijuana's long-term risks. The research, paid for by the British Health Department, is being published Friday in medical journal The Lancet.

"The available evidence now suggests that cannabis is not as harmless as many people think," said Dr. Stanley Zammit, one of the study's authors and a lecturer in the department of psychological medicine at Cardiff University.

Source: Yahoo News

[Professor S]

Honestly, I need to see some hard numbers on this. When researchers start emphasizing only their percentage results with no context, I'm always doubtful as to the impact of the research.

So how can a 40% increased risk not be harmful?

Well, if your original risk of "psychosis" was 1 in 4,239,389.3, and smoking weed made it [b]2 in 4,239,389.3, thats a 100% increase but your odds are still pretty damn slim.

Its all in the numbers, not in the percentages.

[Bond]

Here's some more information, but it's still rather vague:

"Zammit and colleagues from the University of Bristol, Imperial College and Cambridge University examined 35 studies that tracked tens of thousands of people for periods ranging from one year to 27 years to examine the effect of marijuana on mental health.

They looked for psychotic illnesses as well as cognitive disorders including delusions and hallucinations, bipolar disorder, depression, anxiety, neuroses and suicidal tendencies.

They found that people who used marijuana had roughly a 40 percent higher chance of developing a psychotic disorder later in life. The overall risk remains very low.

For example, Zammit said the risk of developing schizophrenia for most people is less than 1 percent. The prevalence of schizophrenia is believed to be about five in 1,000 people. But because of the drug's wide popularity, the researchers estimate that about 800 new cases of psychosis could be prevented by reducing marijuana use.

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 percent to 200 percent."

[The Germanator]

Originally Posted by Bond

Here's some more information, but it's still rather vague:

"They looked for psychotic illnesses as well as cognitive disorders including delusions and hallucinations

Isn't that supposed to be part of the fun?

[Professor S]

The numbers in the quote Bond posted are some of the most irresonsible I;ve ever seen by a scientist. He mixes different numbers together.

For example, Zammit said the risk of developing schizophrenia for most people is less than 1 percent. The prevalence of schizophrenia is believed to be about five in 1,000 people. But because of the drug's wide popularity, the researchers estimate that about 800 new cases of psychosis could be prevented by reducing marijuana use.

So its 5 in 1,000 normally (.5% chance, BTW), but reducing weed use would stop 800 new cases? 800 new cases out of how many in the pool? 10,000? 100,000? 1,000,000? The world?

There is also the argument of causation vs. correlation. They are including depression in their numbers. Now are they depressed due to the weed, or do those that are depressed tend to gravitate towards its use?

There are so many questions to consider.

[Perfect Stu]

Originally Posted by Professor S

There is also the argument of causation vs. correlation. They are including depression in their numbers. Now are they depressed due to the weed, or do those that are depressed tend to gravitate towards its use?

There are so many questions to consider.

I assume they would only consider cases where depression/other symptoms are new to the user AFTER initial use of the weed. Otherwise, the study would be a joke. I can say with absolute confidence that people who suffer from varying levels of depression are more likely to use weed.

[manasecret]

I think it's fishy just by their use of the word 'psychotic'. Isn't psychosis just an umbrella term for pretty much any disorder of the mind? I mean, which psychosis?

According to Wikipedia:

Some studies indicate that cannabis use may lower the threshold for psychosis, and thus help to trigger full-blown psychosis in some people.[70] Early studies have been criticized for failing to consider other drugs (such as LSD) that the participants may have used before or during the study, as well as other factors such as pre-existing ("comorbid") mental illness. However, more recent studies with better controls have still found a small increase in risk for psychosis in cannabis users[citation needed]. It is not clear whether this is a causal link, and it is possible that cannabis use only increases the chance of psychosis in people already predisposed to it; or that people with developing psychosis use cannabis to provide temporary relief of their mental discomfort. The fact that cannabis use has increased over the past few decades, whereas the rate of psychosis has not, suggests that a direct causal link is unlikely for all users.[71]

[gekko]

Considering the type of people who use drugs vs. the type who does not, I'm not sure if the weed causes it. It may be a personality they have, which leads them not only to drugs, but to being psychotic.

[Bond]

Nothing quite like a classic bottle of Bayer:

[GameMaster]

This one turned out to be totally wrong. Apparently a correlation between marijuana use and psychosis doesn't necessarily mean that marijuana caused the psychosis. Many of the researchers made this clear in their findings, but reporters left it out. Furthermore, none of the stories on this topic explained that the risk of psychosis is small, so a 40% increase isn't that significant to begin with. Reporters also failed to observe that massive increases in marijuana use over the past century have not corresponded with increased rates of psychosis.

http://stopthedrugwar.org/chronicle_...a_does_not_cau