Over the past 50 years, anecdotal reports linking
cannabis sativa (marijuana) and psychosis
have been steadily accumulating, giving rise
to the notion of “cannabis psychosis.” Despite this historic
connection, marijuana often is regarded as a “soft
drug” with few harmful effects. However, this benign
view is now being revised, along with mounting research
demonstrating a clear association between cannabis
and psychosis.
In this article, I review evidence on marijuana’s impact
on the risk of developing psychotic disorders, as
well as the potential contributions of “medical” marijuana
and other legally available products containing
synthetic cannabinoids to psychosis risk.

http://www.currentpsychiatry.com/pdf...9CP_Pierre.pdf