title: Effectiveness of a marijuana expectancy manipulation: Piloting the balanced-placebo design for marijuana.
abstract: Although alcohol and nicotine administration studies have demonstrated that manipulating subjects' expectancies regarding drug content affects drug response, research with marijuana has not adequately studied drug expectancy effects. The present pilot study was the first to evaluate the credibility and effect of expectancy manipulation on subjective measures and smoking patterns using a marijuana administration balanced-placebo design (BPD). In a 2 x 2 instructional set (told delta-9-tetrahydrocannabinol [THC] vs. told no THC) by drug (smoked marijuana with 2.8% THC vs. placebo) between-subjects design, the authors examined the effect of marijuana expectancy manipulation and the pharmacologic effect on affective and physiologic measures, cigarette ratings, and smoking behavior with 20 marijuana smokers (mean age = 20 years; 25% female). Large main effects of expectancy were found on ratings of cigarette potency, strength, taste, smell, and satisfaction, and observed smoking behavior. Pharmacologic effects were particularly evident for self-reported physical reactions to marijuana and cigarette potency and satisfaction ratings. This study demonstrated the feasibility of the BPD research with marijuana and yielded promising results for future studies examining the independent and combined effects of marijuana pharmacology and expectancies.
authors: Center for Alcohol and Addiction Studies, Brown University, Providence, RI 02912, USA. Jane_Metrik@brown.edu
authors: Jane
authors: J
authors: Metrik
authors: Damaris J
authors: DJ
authors: Rohsenow
authors: Peter M
authors: PM
authors: Monti
authors: John
authors: J
authors: McGeary
authors: Travis A R
authors: TA
authors: Cook
authors: Harriet
authors: H
authors: de Wit
authors: Margaret
authors: M
authors: Haney
authors: Christopher W
authors: CW
authors: Kahler
mesh_terms: D000293:Adolescent; D000328:Adult; D000339:Affect / Q000187:drug effects; D001290:Attitude; D013759:Dronabinol / Q000008:administration & dosage* / Q000494:pharmacology; D005260:Female; D006801:Humans; D008297:Male; D008385:Marijuana Smoking / Q000523:psychology*; D010865:Pilot Projects; D010919:Placebos
chemical_list: D010919:Placebos; D013759:Dronabinol