"Not only does marijuana not cause depression, it looks like it may actually alleviate it," said Mitch Earleywine, co-author of the new study and associate professor of psychology at the University at Albany, State University of New York.

The new study adds to a growing body of knowledge suggesting that marijuana's active components, called cannabinoids, may be beneficial in certain psychological disorders. In a review published this May in the Journal of Psychopharmacology, researchers form the University of Newcastle upon Tyne in Great Britain noted, "Patient reports and observations, backed by known pharmacology, suggest that the cannabis derivatives delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) may have mood stabilizing properties," including anti-depressant and anti-anxiety effects.

http://www.mpp.org/releases/nr20051117.html