SMH: Recent Developments on the Self-Medication Hypothesis

Denson, T. F., and Earleywine, M. (2006). Decreased depression in marijuana users. Addictive Behavior, 31(4), 738-742.

Denson and Earleywine 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. Their survey resulted in a sample consisting of over 4,400 adult internet users each of whom completed The Center for Epidemiologic Studies Depression (CESD) scale and a measure of marijuana use.

They compared the CESD scores of three groups: those whose marijuana consumption was daily, once a week or less, and never in their lives. Both user groups (daily and once per week or less) reported less depressed mood and more positive affect than non-users. Those who used once per week or less also reported significantly fewer somatic complaints 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. Medical users, while reporting more depressed mood than recreational users, still reported less than did non-users. The researchers concluded that adults apparently do not increase their risk for depression by using marijuana.

Contact: Thomas F. Denson, University of Southern California, Seeley G. Mudd Building, Room 501, Los Angeles, CA 90089-1061, United States. denson@usc.edu