Psychotherapeutic interventions for cannabis abuse and/or dependence in outpatient settings

BACKGROUND: Cannabis use disorder is the most common illicit substance use disorder in general population. Despite that, only a minority seek assistance from a health professional, but the demand for treatment is now increasing internationally. Trials of treatment have been published but to our knowledge, there is no published systematic review . OBJECTIVES: To evaluate the efficacy of psychosocial interventions for cannabis abuse or dependence. SEARCH STRATEGY: We searched the Cochrane Central Register of Trials (CENTRAL) The Cochrane Library Issue 3, 2004; MEDLINE (January 1966 to August 2004), PsycInfo (1985 to October 2004), CINAHL (1982 to October 2004), Toxibase (until September 2004) and reference lists of articles. We also contacted researchers in the field. SELECTION CRITERIA: All randomised controlled studies examining a psychotherapeutic intervention for cannabis dependence or abuse in comparison with a delayed-treatment control group or combinations of psychotherapeutic interventions. DATA COLLECTION AND ANALYSIS: Two authors independently assessed trial quality and extracted data MAIN RESULTS: Six trials involving 1297 people were included. Five studies took place in the United States, one in Australia. Studies were not pooled in meta-analysis because of heterogeneity. The six included studies suggested that counselling approaches might have beneficial effects for the treatment of cannabis dependence. Group and individual sessions of cognitive behavioral therapy (CBT) had both efficacy for the treatment of cannabis dependence and associated problems, CBT produced better outcomes than a brief intervention when CBT was delivered in individual sessions. Two studies suggested that adding voucher-based incentives may enhance treatment when used in combination with other effective psychotherapeutic interventions. Abstinence rates were relatively small overall but favoured the individual CBT 9-session (or more) condition. All included trials reported a statistically significant reductions in frequency of cannabis use and dependence symptoms. But other measures of problems related to cannabis use were not consistently different. AUTHORS' CONCLUSIONS: The included studies were too heterogenous and could not allow to draw up a clear conclusion. The studies comparing different therapeutic modalities raise important questions about the duration, intensity and type of treatment. The generalizability of findings is also unknown because the studies have been conducted in a limited number of localities with fairly homogenous samples of treatment seekers. However, the low abstinence rate indicated that cannabis dependence is not easily treated by psychotherapies in outpatient settings.