Improving functional outcomes in women with borderline personality disorder and PTSD by changing PTSD severity and post-traumatic cognitions.

Although functional impairment typically improves during evidence-based psychotherapies (EBPs) for borderline personality disorder (BPD), functional levels often remain suboptimal after treatment. The present pilot study evaluated whether and how integrating PTSD treatment into an EBP for BPD would improve functional outcomes. Participants were 26 women with BPD, PTSD, and recent suicidal and/or self-injurious behavior who were randomized to receive one year of Dialectical Behavior Therapy (DBT) or DBT with the DBT Prolonged Exposure (DBT PE) protocol for PTSD. Five domains of functioning were assessed at 4-month intervals during treatment and at 3-months post-treatment. DBT + DBT PE was superior to DBT in improving global social adjustment, health-related quality of life, and achieving good global functioning, but not interpersonal problems or quality of life. Results of time-lagged mixed effects models indicated that, across both treatments, reductions in PTSD severity significantly predicted subsequent improvement in global social adjustment, global functioning, and health-related quality of life, whereas reductions in post-traumatic cognitions significantly predicted later improvement in all functional outcomes except global social adjustment. These findings provide preliminary evidence supporting the role of change in PTSD severity and trauma-related cognitions as active mechanisms in improving functional outcomes among individuals with BPD and PTSD.