I think if you looked hard enough you'd find that none of the research done indicates that pot use causes psychosis (and no, I haven't touched the stuff in years), well depending on how you define psychosis - does giggling uncontrolably at Fast Food Drive Though Windows Count?

Here's a link to a sort of debunking of the pot causes schizophrenia crap:

http://www.badscience.net/2007/07/blah-blah-cannabis-blah-blah-blah/#more-476

Besides, here's a drug that we all know causes psychosis - alcohol. Another one, Prozac....

Got to love the scientific study of depression in non-human animals.

Marijuana Improves Depression in Low Doses, Worsens It in High Doses, Study Says Thursday, October 25, 2007
During the study, published in the October 24 issue of The Journal of Neuroscience, laboratory rats were injected with the synthetic cannabinoid WIN55,212-2 and then tested with the Forced Swim test — a test to measure “depression” in animals.

http://www.foxnews.com/story/0,2933,304996,00.html

LINK

Here's another take on Schizophrenia and nicotine Nicotine use and its correlates in patients with psychosis.

"We could not find any differences among nicotine users and non-users in diagnosis, symptoms, side effects, weight, cognitive functions, personality and outcome, cross-sectionally and longitudinally, ruling against the ‘self-medication’ hypothesis."

Makes me think psych wards/etc. should have 'pot breaks', instead of 'smoke breaks'. It also makes me think we are far off from any solid answers for treatment.

Marijuana may generally be more helpful than harmful for most people (at least in small amounts), and it may not ever directly cause schizophrenia or any other kind of psychotic break. But some people are more sensitive to it than most, and for some it can exacerbate an already difficult situation. Unless a person knows how it will affect them personally, it should not be assumed that it will be harmless. Everyone is different in the way they will be affected by marijuana, as they are in the way they are affected by all kinds of drugs, and caution is always called for.

The potential of marijuana to cause problems is not just theoretical, but based on personal experiences that some people have had. For some it can lead to sleep deprivation, for example(which is seldom a good thing), as can be seen in the narrative linked to below:

http://www.mindfreedom.org/personal-stories/david-w-oaks/

My problem with the psuedo studies that claim marijuana causes mental illness are along these lines. My father suspected when I was a teenager that I smoked marijuana. For years he used this as proof that I was mentally ill. So if we accept these studies as valid, the bad guys use them to claim that anyone who has ever smoked marijuana needs an anti psychotic med - just wait...still some people have good reactions to it, some don't. For me, pot usually was a lot of fun but sometimes it made me extremely anxious to the point where I decided not to use it again many years ago.