Although marijuana itself has shown no clinical benefit for the treatment of depression, University of Irvine researchers have shown that one of its active ingredients produces antidepressant effects.

The brain naturally produces the enzyme anandamide, which is nicknamed the ‘bliss molecule’ because of its similarities to the active ingredient in marijuana and its anti-depressant qualities. The idea was to prevent the breakdown of the anandamide enzyme in the brain caused by the enzyme fatty acid amide hydrolase (FAAH).

Researchers used experimental drug URB597, which blocks FAAH degradation of the anandamide enzyme in the brain. To test the effectiveness of their drug they administered URB597 to chronically stressed rats, which demonstrate behaviors similar to those seen in depressed human patients. Following 5 weeks of treatment the behavior of the stressed rats treated with URB597 was similar to the control group of unstressed rats.

A patent for URB597 was issued to the European pharmaceutical company Organon in 2007. Clinical studies for the drug are expected to begin in 2008.