Decreased depression in marijuana users.

Over 4400 adult internet users completed The Center for Epidemiologic Studies Depression scale and measures of marijuana use. We employed an internet survey in an effort to recruit the most depressed and marijuana-involved participants, including those who might prove unwilling to travel to the laboratory or discuss drug use on the phone or in person. We compared those who consumed marijuana 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 complaints than non-users. Daily users reported less depressed mood and more positive affect than non-users. The three groups did not differ on interpersonal symptoms. Separate analyses for medical vs. 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.