Researchers at the University of Southern California analyzed survey results from 4,400 adults who had completed The Center for Epidemiologic Studies Depression scale (a numerical, self-report scale designed to assess symptoms of depression in the general population). Authors compared "depression scores" among those who consumed cannabis daily, once a week or less, or never in their lives.

"Despite comparable ranges of scores on all depression subscales, those who used once per week or less had less depressed mood, more positive affect, and fewer somatic (physical) complaints than non-users," authors wrote. "Daily users [also] reported less depressed mood and more positive affect than non-users."

Authors further noted that a separate analysis of medical cannabis users versus recreational users "demonstrated that medical users reported more depressed mood and more somatic complaints than recreational users, suggesting that medical conditions clearly contribute to depression scores and should be considered in studies of marijuana and depression.

"These data suggest that adults apparently do not increase their risk for depression by using marijuana," researchers concluded.

For more information, please contact Paul Armentano, NORML Senior Policy Analyst, at (202) 483-5500. Full text of the study, "Decreased depression in marijuana users," appears in the June issue of Addictive Behaviors.