http://www.abc.net.au/quantum/poison/marijuan/about.htm

Marijuana is a drug that divides people. Some people herald it as the wonder drug of the '90s, capable of relieving the symptoms of many serious illnesses. Others rue the day the cannabis sativa plant was ever discovered.

As well as being morally corrupting, its critics say it causes brain damage and is carcinogenic.Naturally this is all very confusing for people who smoke the drug and who want information. The drug's illegal status doesn't help. It makes it difficult for scientists to research the effects of the drug. Also it means the sort of health advice and health care that should be available is restricted.

Fortunately, it is possible to separate fact from fiction. Marijuana is neither completely harmless, or as dangerous as some people say. Rather, the truth lies somewhere in the middle. Undoubtedly it is useful as a pain reliever or in the treatment of nausea - a great help to AIDS patients.

But the harmless hippy image of marijuana is being tested by the latest Australian research into the connection between cannabis and psychosis. It seems that marijuana use can act as a trigger for the progression of mental illness in some people. How this comes about is still being investigated, but it seems likely that cannabis alters the flow of a naturally occurring transmitter chemical in our brains. The same chemical, if it malfunctions, is linked with he development of schizophrenia. The program signals a warming for people at risk.