Relationships between motivation and depression in chronic marijuana users.

The "amotivational syndrome" which has been associated with marijuana use has not been examined systematically in relation to marijuana use and mental health. Light and heavy users were solicited by personal contact. They were asked to complete anonymous questionnaires which measured marijuana, alcohol and cocaine use, perceived states during marijuana intoxication, depressive symptoms in the last year, the Orientation to Life Scale and a modified form of the Thematic Apperception Test, from which Need for Achievement, Affiliation and Power were assessed. Several group comparisons were made: Chronic heavy-users (medians: daily use for 6 years) with and without significant symptoms of depression within the last year were compared with Light users (medians: several times per month for 4.5 years) with and without significant symptoms of depression within the last year. Subjects in all groups reported similar ratings of intoxication (being stoned) during marijuana use. No differences were found in alcohol or cocaine use among the comparison groups. Scores on Need for Achievement were significantly lower in heavy users with depressive symptoms when compared with all other groups. No effects were found among groups in measures of the Need for Affiliation and the Need for Power. Both light and heavy users with symptoms of depression had significantly lower scores than those without depressive symptoms, on the overall Orientation to Life questionnaire and on each subscale measuring Meaningfulness, Manageability and Comprehensibility. These data suggest that amotivational symptoms observed in heavy marijuana users in treatment are due to depression.