Aims: Achieving abstinence in the treatment of marijuana dependence has been difficult. To date the most successful treatments have included combinations of motivation enhancement treatment (MET) plus cognitive-behavioral coping skills training (CBT) and/or contingency management (ContM) approaches. Although these treatment approaches are theoretically based, their mechanisms of action have not been explored fully. The purpose of the present study was to explore mechanisms of behavior change from a marijuana treatment trial in which CBT and ContM were evaluated separately and in combination.
Design: A dismantling design was used in the context of a randomized clinical trial.
Setting: The setting was an out-patient treatment research facility located in a university medical center.
Participants: Participants were 240 adult marijuana smokers, meeting criteria for cannabis dependence.
Interventions: Participants were assigned to one of four 9-week treatment conditions: a case management control condition, MET/CBT coping skills training, ContM and MET/CBT + ContM.
Measurements: Outcome measures were total 90-day abstinence, recorded every 90 days for 12 months post-treatment.
Findings: Regardless of treatment condition, abstinence in near-term follow-ups was predicted most clearly by abstinence during treatment, but long-term abstinence was predicted by use of coping skills and especially by post-treatment self-efficacy for abstinence.
Conclusions: It was concluded that the most efficacious treatments for marijuana dependence are likely to be those that increase self-efficacy.