Teenagers, dope and depression

Teenagers suffering from depression sometimes use alcohol, cigarettes and illegal drugs to alleviate their negative feelings. Depressed teenagers are more than twice as likely than non-depressed teenagers to use cannabis and other illegal drugs. However, by using cannabis to 'self-medicate' they could be making the situation worse. Teenagers who smoke cannabis at least once a month are three times more likely to have suicidal thoughts than non-users and cannabis use has also been linked to an increased risk of schizophrenia and psychosis.

http://psychcentral.com/news/2008/05/09/drugs-depressed-teens-a-dangerous-combination/2264.html