Smoking Pot Won't Make You Crazy, But Dealing with the Lies about It Will
By Paul Armentano and Mitch Earlywine

Smoking pot won't make you crazy, but trying to find the truth behind the recent rash of headlines regarding a supposed link between cannabis and mental illness might.
According to the Associated Press and other news sources, a new study in the British medical journal The Lancet reports that smoking cannabis -- even occasionally -- can increase one's risk of becoming psychotic. It sounds alarming at first, but a closer look at the evidence reveals that there's less here than the headlines imply.
First, there is no new study. The paper published in The Lancet is a meta-analysis -- a summary of seven studies that previously appeared in other journals, including some that were published decades ago. Second, the touted association between cannabis and mental illness is small -- about the same size as the link between head injury and psychosis. Finally, despite what some new sources suggest, this association is hardly proof of a cause-and-effect relationship between cannabis and psychosis, So why the sudden fuss? LINK