Effects of mindfulness-based interventions on depressive symptoms in patients with substance use disorders: a systematic review and meta-analysis

Abstract Objective We examined the effects of mindfulness-based interventions (MBIs) on depressive symptoms in patients with substance use disorders (SUDs) and explored the moderating effects of participant, method, and intervention characteristics. Methods We systematically searched 8 databases from their inception till November 2021. The inclusion criteria were primary studies evaluating MBIs in patients with SUDs with depression measured as an outcome, those including a control group, and those written in English. We used a random-effects model to compute effect sizes (ESs) using Hedges’ g, a forest plot, and Q and I2 statistics as measures of heterogeneity; we also examined moderator analyses. Results Nineteen studies included 1352 participants (age: 38.6 ± 7.0 years). Overall, MBIs showed significantly improved depression (g = 0.67, 95% confidence interval [CI]: 0.29, 1.05, I2 = 89%) compared to controls. With regard to moderators, providing MBIs as an individual plus group intervention had a greater effect (g = 2.13) on reducing depressive symptoms than providing MBIs as a group intervention (g = 0.64) or an individual intervention only (g = 0.33, P = 0.034). Using concealed allocation tended to reduce depressive symptoms (g = 1.22) as compared to not using concealed allocation (g = 0.48, P = 0.086). No other quality indicators were demonstrated to have a moderating influence on the value of the ES. Conclusions MBIs improved depressive symptoms in patients with SUDs. MBIs might be used as an adjunctive or alternative to conventional treatment for depressed patients with SUDs.