A meta-analysis of the effect of substance use interventions on emotion outcomes

Objective: Emotional distress has been posited as a key underlying mechanism in the development and maintenance of substance use disorder (SUD), and patients seeking SUD treatment are often experiencing high levels of negative emotion and/or low levels of positive emotion. But the extent to which SUD interventions impact emotional outcomes among general SUD populations is yet unquantified. The current meta-analysis aims to fill this gap. Method: A total of 11,754 records were screened for randomized, controlled trials examining the effect of behavioral SUD interventions on emotion outcomes. Our search yielded a total of 138 effect sizes calculated based on data from 5,146 individuals enrolled in 30 independent clinical trials. Random-effects meta-analysis was used to calculate pooled effect sizes, and metaregression analyses examined study-level moderators (e.g., intervention type). Results: Findings indicated a small but significant effect of SUD interventions on emotion outcomes, d = 0.157, 95% CI [0.052, 0.262] (k = 30). The effect size for negative emotion was nominally bigger, d = 0.162, 95% CI [0.056, 0.269] (k = 30), whereas the effect for positive emotion did not reach statistical significance, d = 0.062, 95% CI [-0.089, 0.213] (k = 7). Studies featuring SUD interventions designed to specifically target emotions (i.e., affect-regulation, mindfulness-based treatments) produced larger reductions in negative emotion compared with studies featuring interventions that did not contain specific emotion modules (e.g., contingency management). Conclusions: Findings suggest that SUD interventions- especially mindfulness-based and affect-regulation treatments-indeed significantly reduce negative emotion, although relatively small effect sizes indicate potential room for improvement. Conclusions regarding positive emotion should be considered preliminary because of the limited numbers of samples assessing these outcomes.