We used the DSM-IV abuse and dependence symptoms to obtain a measure of cannabis abuse/dependence. Questions to assess abuse/dependence were also only asked on those using 11 or more times and at least monthly during the heaviest period of use. For cannabis abuse the criteria were: (1) recurrent use resulting in a failure to fulfill major obligations at work, school, or home, (2) recurrent use in situations which are physically hazardous, (3) continued use despite significant social or interpersonal problems caused by the substance use, and (4) continued use despite legal problems. The criteria for cannabis dependence were: (1) an increase in use to achieve an effect (tolerance), (2) using more frequently or for longer periods than intended, (3) persistent desire or unsuccessful efforts to cut down or control substance use, (4) a great deal of time is spent in activities necessary to obtain the substance, use the substance, or recover from its effects, (5) important social, occupational, or recreational activities are given up or reduced because of substance use, and (6) the substance use is continued despite knowledge of
