This meta-analysis used data from 34 studies of non-pharmacological therapies for addictive disorders, including 2,340 patients – 5 studies of cannabis use, 9 for cocaine, 7 for opiate, and 13 for polysubstance use.1 As shown on the slide, the results generally suggested that non-pharmacological treatments were beneficial, with low-to-moderate effect sizes, in the treatment of the various substance-use disorders studies.1 However, the low numbers of studies available for inclusion reduce the certainty of some of the conclusions.1

Reference:
[1] Dutra L, Stathopoulou G, Basden SL, et al. A meta-analytic review of psychosocial interventions for substance use disorders. Am J Psychiatry 2008; 165 (2): 179–187.