Operant acquisition of marihuana by women.

Marihuana acquisition and use patterns were studied in 21 women on a clinical research ward. Women could earn one 1-g marihuana cigarette or 50 cents in 30 min of performance on a second-order Fixed-Ratio 300 (Fixed-Interval 1 sec:S) schedule of reinforcement. A 7-day drug-free base line was followed by 21 days of marihuana availability and a postmarihuana drug-free period of 7 days. Five heavy marihuana users smoked an average of 6.1 (+/- 1.45) marihuana cigarettes per day and increased marihuana use significantly through time (P less than .001). Seven moderate marihuana users smoked an average of 2.72 (+/- 0.16) marihuana cigarettes per day and used significantly less marihuana through time (P less than .01). Nine occasional marihuana users smoked less than one cigarette per day (0.90 +/- 0.22) and maintained stable patterns of marihuana use. Women who increased marihuana use during the premenstruum reported significantly greater premenstrual dysphoria on the Premenstrual Assessment Form than women whose marihuana use decreased or remained the same (P less than .05 to .01). There were no marihuana dose-related effects on operant performance. The heavy, moderate and occasional marihuana smokers did not differ in operant purchase points earned, hours worked or money earned. Each marihuana dose-group earned an equivalent number of purchase points during the drug-free periods and the period of marihuana availability. Some subjects continued to work for money when smoking 15 to 20 marihuana cigarettes per day and periods of maximal operant work coincided with periods of maximal marihuana smoking (noon-midnight).(ABSTRACT TRUNCATED AT 250 WORDS)