The role of mindfulness and emotion regulation in dialectical behavioral therapy for borderline personality disorder.

Despite nearly 30 years of research demonstrating its effectiveness in the treatment of borderline personality disorder (BPD) and related problems, few studies have investigated mechanisms of change for dialectical behavior therapy (DBT; Linehan, 1993a). Improvements in mindfulness and emotion regulation have been highlighted as key potential mechanisms of change in DBT (Lynch et al., 2006). The present study examined the time course of and associations between mindfulness, emotion regulation, and BPD symptoms during DBT. Participants were 240 repeatedly and recently self-harming adults (M_age = 27.75) with BPD who were randomly assigned to receive either 6 or 12 months of standard DBT. Primary hypotheses were that: (a) changes in mindfulness would occur before changes in emotion regulation, and (b) changes in emotion regulation would mediate the association of changes in mindfulness with changes in BPD symptoms. Results from changepoint analysis illuminated the proportion of participants for whom first changes occurred in emotion regulation (40.7%), mindfulness (32.4%), or both (26.9%). Contrary to hypotheses, five-wave, cross-lagged analyses did not indicate mediational effects of either mindfulness or emotion regulation on the association of either variable with change in BPD symptoms. Supplemental analyses, however, suggested that changes in emotion regulation mediated the inverse association of changes in mindfulness with changes in BPD symptoms. Findings highlight patterns of change in key, proposed mechanisms of change in DBT and suggest important future research directions. (PsycInfo Database Record (c) 2024 APA, all rights reserved).