A systematic review and meta-analysis of the relative and complementary effects of motivational interviewing and cognitive-behavioral treatment for problem gambling and gambling disorder.

Objective: To compare the relative and complementary effects of motivational interviewing (MI) and cognitive-behavioral treatment (CBT) for problem gambling and gambling disorder.

Method: Four bibliographic databases were searched to identify published and unpublished studies of randomized controlled trials of participants with problem gambling and gambling disorder. Participants were randomized to a combined MI + CBT condition and a control condition of either MI only or CBT only. A correlated, hierarchical effects meta-analysis was conducted, pooling Hedges's g effect sizes for MI + CBT versus MI only and MI + CBT versus CBT only at posttreatment and follow-up. Outcomes included gambling behavior (i.e., number of times gambled, money spent gambling, time spent gambling) and gambling disorder severity.

Results: Eight studies representing 1,078 participants were included. Five studies examined the additive effect of MI (i.e., MI + CBT vs. CBT only), and three studies examined the additive effect of CBT (i.e., MI + CBT vs. MI only). Compared with CBT only, MI + CBT showed significantly less gambling behavior and gambling disorder severity at posttreatment (g = -0.17, 95% CI = -0.31, -0.04) but not at follow-up (g = -0.17, 95% CI = -0.48, 0.13). By contrast, MI + CBT did not significantly differ from MI only at posttreatment (g = -0.05, 95% CI = -0.51, 0.41) or follow-up (g = -0.10, 95% CI = -0.47, 0.26).

Conclusions: Overall, findings were more consistent with a complementary and context-dependent model in which MI and CBT interact rather than exert uniform additive effects. The effectiveness of motivational and skills-based components for treating problem gambling and gambling disorder may depend on how they are integrated. (PsycInfo Database Record (c) 2026 APA, all rights reserved).