While at least two studies have found an association between cannabis use and schizophrenia, none have established that pot causes the symptoms associated with the disease.
Now, in the first study that bothers to ask schizophrenics why they take the drug, patients report using pot to ease some of their tormenting symptoms:
“The findings indicate that cannabis is used as a means of satisfying the schizophrenia-related need for relaxation, sense of self-worth, and distraction. The findings may be useful for nurses working with persons who have schizophrenia, a population that is frequently stigmatized and unheard.”
via Attraction to cannabis among men with schizophreni… [Can J Nurs Res. 2010] – PubMed result.

I think developing discussions in California around legalizing cannibis on a widespread basis could change perceptions about its use in medicinal and even just plain old recreational ways. Legalizing it would have a seismic effect on the drug’s production, consumption and public image…
Perhaps long overdue.
As for the schizophrenia connection, mainstream physicians have long been ambivalent about marijuana’s impact on health, never quite committing themselves to saying it has outright detrimental effects like cigarettes or alcohol.
Anyway, maybe the riskiest side effect of the drug’s consumption is the overeating that sometimes follows…