Despite research supporting the effectiveness of dialectical behavior therapy (DBT) for borderline personality disorder (BPD), few studies have examined how DBT leads to clinical change. DBT is theorized to lead to improved clinical outcomes by enhancing the capacity for emotion regulation, including improvement in skills (e.g., mindfulness and distress tolerance) for managing emotional distress and impulsive behaviors. Therefore, the aim of this study was to test whether improvements in mindfulness and distress tolerance indirectly affect the relationship between DBT skills training and clinical outcomes. The sample consists of 84 patients diagnosed with BPD who were enrolled in a randomized controlled trial comparing 20 weeks of DBT-skills group (DBT-S) to an active waitlist control. Mindfulness and distress tolerance were assessed at baseline and at the end of the 20 weeks. BPD symptoms, general psychiatric symptoms, and social adjustment were assessed at the end of 20 weeks and combined into a latent variable representing a broad assessment of general psychopathology. Relative to the waitlist control group, improvements in mindfulness and distress tolerance each independently indirectly affected the relationship between DBT-S and posttreatment general psychopathology. Findings suggest that DBT-S exerts its effects on outcomes through improvements in mindfulness and distress tolerance. These findings support the significance of mindfulness and distress tolerance in DBT-S for BPD. Limitations, future directions, and clinical implications are discussed. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
Trial registration: ClinicalTrials.gov NCT01193205.