This is a little of topic but just to clear up some things about cannabis and schizophrenia. So far it has been found that there is a casual link between heavy cannabis use and the later development of schizophrenia. This does not mean that heavy cannabis use will cause schizophrenia as there are many people who use cannabis heavily and do not go on to develop schziophrenia. What it means is that when combined with other predispositions to the development of schizophrenia (ie. genetic succeptabilty, severly traumatic experiences etc.) then cannabis use can increase the liklihood of developing schizophrenia in succeptable individuals. Many of the individuals who used cannabis heavily would have gone on to develop schizophrenia anyway, whilst for others the heavy smoking was the straw that broke the camel's back (they were succeptable but without the smoking may not have developed schizophrenia). There have been many studies on this, including the 'Swedish Cohort study' which from memory found that heavy users of cannabis were 3 times more likely to develop schizophrenia than those who didn't smoke cannabis.
A distinction also should be made between somebody having a psychotic episode and developing schizophrenia. A psychotic episode is an acute period of mental distress defined generally by delusions and hallucinations. In the case of cannabis psychosis it typically will only last as long as cannabis use is continued to a couple of weeks after use has ceased. Schizophrenia is similiar to psychosis but is much more chronic and long lasting.
Anyway, there is some good discussion here guys. Keep em coming!
