Abstinence symptoms following smoked marijuana in humans

Symptoms of withdrawal after oral Delta(9)-tetrahydrocannabinol (THC) admin istration have been reported, yet little is known about the development of dependence on smoked marijuana in humans. In a 21-day residential study, ma rijuana smokers (n = 12) worked on five psychomotor tasks during the day (0 915-1700 hours), and in the evening engaged in recreational activities (170 0-2330 hours); subjective-effects measures were completed 10 times/day. Foo d and beverages were available ad libitum from 0830 to 2330 hours. Marijuan a cigarettes (0.0, 1.8, 3.1% THC) were smoked at 1000, 1400, 1800, and 2200 hours. Placebo marijuana was administered on days 1-4. One of the active m arijuana doses was administered on days 5-8, followed by 4 days of placebo marijuana (days 9-12). The other concentration of active marijuana cigarett es was administered on days 13-16, followed by 4 days of placebo marijuana (days 17-20); the order in which the high and low THC-concentration marijua na cigarettes were administered was counter-balanced between groups. Both a ctive doses of marijuana increased ratings of "High," and "Good Drug Effect ," and increased food intake, while decreasing verbal interaction compared to the placebo baseline (days 1-4). Abstinence from active marijuana increa sed ratings such as "Anxious," "Irritable," and "Stomach pain," and signifi cantly decreased food intake compared to baseline. This empirical demonstra tion of withdrawal from smoked marijuana may suggest that daily marijuana u se may be maintained, at least in part, by the alleviation of abstinence sy mptoms.