Exploring the role of mindfulness, emotion regulation, and distress tolerance during delivery of a Dialectical Behaviour Therapy app for recurrent binge eating

Mindfulness, emotion regulation, and distress tolerance are hypothesised mechanisms that underpin Dialectical Behaviour Therapy (DBT) for binge eating, yet their role in app-based interventions is unclear. This study examined whether (1) a digital DBT app improved these skills compared to a control condition and (2) baseline skill levels predicted post-treatment symptom change. This secondary analysis drew on data from a randomised controlled trial (<i>n</i> = 576) of adults with recurrent binge eating. Participants in the intervention (<i>n</i> = 287) completed a six-week self-guided DBT app, while controls (<i>n</i> = 289) were waitlisted. Mindfulness, emotion regulation, and distress tolerance were assessed at baseline, post-test, and 12-week follow-up. Outcomes were binge eating episodes and the Eating Disorder Examination Questionnaire (EDEQ). Linear mixed models tested treatment effects, while univariate and multivariate models assessed baseline predictors. The app produced small-to-moderate improvements in four emotion regulation facets-lack of emotional clarity (d = -0.33), limited strategies (d = -0.22), difficulty with goal-directed behaviour (d = -0.28), and non-acceptance (d = -0.30)-and in the mindfulness facet of observing (d = 0.28). No group differences emerged for distress tolerance. Baseline non-acceptance predicted EDEQ improvement in univariate analyses, but not objective binge eating or multivariate models. A self-guided DBT app may strengthen components of mindfulness and emotion regulation. These results may point towards possible mechanisms through which DBT treatments work. That core DBT skills at baseline were unrelated to outcomes suggesting that they may bear little prognostic value, however may be suitable for broad implementation.