Heavy smokers and light smokers of marijuana were compared for general psychological health, stable personality traits, changes in personality induced by long-term use of marijuana, effects of multiple drug use, and the "amotivational syndrome" that is said to result from heavy use of the drug. Results did not indicate any overall pattern of excess psychopathology for either group, although significant differences were found in levels of depression and organicity and in various personality traits. The findings suggest that heavy use of marijuana may be related to already existing depression and that impaired motivation may be a manifestation of depression rather than a consequence of frequent mairjuana use.Abstract Teaser