Combined pharmacotherapy and evidence-based psychosocial Cannabis treatment for youth and selection of cannabis-using friends

Abstract

Background: Theoretical models of behavior change argue that youth should decrease their time with cannabis-using friends and increase their time with non-using friends during treatment. Informed by behavior-change models of recovery and socialization and selection peer-influence models, the current study examined whether combining evidence-based psychosocial treatment with adjunctive pharmacotherapy helps youth decrease their affiliations with cannabis-using friends and increase their affiliations with non-using friends during cannabis misuse treatment.

Methods: Youth ages 15-24 years (51 % male), participated in a double-blind randomized clinical trial that tested the effects of motivational enhancement and cognitive behavioral therapy (MET-CBT) plus topiramate (N = 39) or placebo (N = 26) on cannabis craving and use. Ecological momentary assessment data, collected via smartphones throughout the six-week intervention, assessed youths' time with cannabis-using and non-using friends, cannabis use, and craving in daily life. Multiple group multilevel structural equation modeling tested study hypotheses.

Results: Across the topiramate (48 % completion rate) and placebo (77 % completion rate) conditions, greater time spent with cannabis-using friends promoted greater next day cannabis use and craving (socialization effect). In turn, cannabis craving, but not use, promoted continued selection of cannabis-using friends. This indirect effect was only supported in the placebo condition due to the selection piece of this cycle not being significant for youth who received topiramate. Neither cannabis craving nor use were associated with time with non-using friends the next day.

Conclusions: MET-CBT and adjunctive topiramate pharmacotherapy interrupted youth selection processes. This finding suggests that changing peer affiliations could be one mechanism by which treatments can work.

Keywords: Cannabis-using friends; MET-CBT; Mediation; Peer influence; Topiramate.

Figure 1.. Conceptual diagram of MSEM.

Note. CU=Cannabis-using, a= a path of mediational chain; within-person time with cannabis-using friends predicting cannabis craving/grams smoked the next day, b₁= b₁ path of mediational chain; within-person cannabis craving/grams predicting time with cannabis-using friends the following day, b₂= b₂ path of mediational chain; within-person cannabis craving/grams predicting time with non-using friends the following day, 1a=Hypothesis 1a; in the overall sample, time spent with cannabis-using friends would predict greater cannabis craving the next day, 1b=Hypothesis 1b; in the overall sample, time spent with cannabis-using friends would predict greater grams smoked the next day, 2a=Hypothesis 2a; in the overall sample, cannabis craving would predict greater time with cannabis-using friends the following day, 2b=Hypothesis 2b; in the overall sample, grams smoked would predict greater time with cannabis-using friends the following day, 2c=Hypothesis 2c; in the overall sample, cannabis craving would predict less time with non-using friends the following day, 2d=Hypothesis 2d; in the overall sample, grams smoked would predict less time with non-using friends the following day, 3a=Hypothesis 3a; the a*b₁ craving mediational path would be statistically significant, 3b=Hypothesis 3b; the a*b₁ grams smoked mediational path would be statistically significant, 3c=Hypothesis 3c; the a*b₂ craving mediational path would be statistically significant, 3d=Hypothesis 3d; the a*b₂ grams smoked mediational path would be statistically significant, 4a=Hypothesis 4a; path a for craving would be significantly weaker in the topiramate relative to the placebo condition, 4b=Hypothesis 4b; path a for grams smoked would be significantly weaker in the topiramate relative to the placebo condition; 5a= Hypothesis 5a; path b₁ for craving would be significantly weaker in the topiramate relative to the placebo condition; 5b=Hypothesis 5b; path b₁ for grams smoked would be significantly weaker in the topiramate relative to the placebo condition, 5c=Hypothesis 5c; path b₂ for craving would be significantly stronger in the topiramate relative to the placebo condition, 5d=Hypothesis 5d; path b₂ for grams smoked would be significantly weaker in the topiramate relative to the placebo condition. The level 1 covariate weekend status and within-person covariances between CU friends and non-CU friends are not depicted to reduce figure complexity.