The Marijuana Treatment Project: rationale, design and participant characteristics

Aims Recent findings regarding the prevalence of marijuana dependence and associated consequences indicate the need for empirically validated treatments for this population. The Marijuana Treatment Project (MTP) was a multi-site study of two treatments for adults with marijuana dependence. Design Participants (N = 450) were randomly assigned to one of three conditions at each of three sites: 1) a 9-session cognitive behavioral treatment (CBT) with motivational enhancement therapy (MET) and case management (CM) components; 2) a 2-session MET intervention; or 3) a delayed treatment control (DTC). Setting The study was conducted in outpatient drug treatment clinics in three U.S. cities. Participants Participants were individuals aged 18 or over who met diagnostic criteria for cannabis dependence and who voluntarily presented for treatment: Measurement Study variables included DSM-IV dependence criteria, timeline follow-back assessment of drug use, Addiction Severity Index composite scores,. and problems related to marijuana use. Findings Participants were daily-users, who smoked marijuana multiple times per day, and had been doing so for more than 15 years. They reported multiple dependence symptoms and negative consequences related to marijuana use. Approximately 32% of the sample was female, and 30% of the sample was either Hispanic (17%), African American (12%), or of mixed racial backgrounds (1%). Conclusions The multi-site nature of the MTP allowed for the recruitment of a more ethnically and gender diverse sample than had been studied previously but there were few differences in the clinical characteristics of participants at the geographically and sociodemographically diverse study sites.