BPD Compass: Using a dimensional model of psychopathology to treat co-occurring borderline personality disorder and posttraumatic stress symptoms.

BPD Compass is a transdiagnostic psychotherapy that includes cognitive, behavioral, and mindfulness skills targeting the personality dimensions of negative affectivity, disinhibition, and antagonism. Given considerable symptom comorbidity and overlap in etiology between borderline personality disorder (BPD) and posttraumatic stress disorder (PTSD), this study investigated whether BPD Compass holds promise as an integrated approach to simultaneously treating co-occurring BPD features and PTSD symptoms. Participants included 84 trauma-exposed adults who participated in a two-phase clinical trial (Phase 1: randomized controlled trial of BPD Compass vs. waitlist [n = 43]; Phase 2: open trial of BPD Compass [n = 41]). Compared to waitlist, BPD Compass led to medium-to-large-sized, significant improvements in BPD features, βs = -.57 -.44, and facets of neuroticism, βs < -.55--.73, as well as small, nonsignificant improvements in self-reported, β = -.20, and clinician-rated PTSD symptom severity, β = -.19. During treatment, within-person improvements in PTSD symptoms predicted subsequent improvements in BPD features, β = .13, but not vice versa, β = .07. Within-person PTSD symptom reduction also predicted subsequent improvement in all personality dimensions, whereas only within-person improvement in despondence, β = .12, affective dysregulation, β = .11, and dissociative tendencies, β = .12, predicted PTSD symptom reductions. Findings offer preliminary support for the potential of BPD Compass to target BPD features and aspects of neuroticism and agreeableness among trauma-exposed adults. Moreover, PTSD symptom change predicting subsequent improvement in BPD features runs counter to current stage-based treatment models that emphasize BPD feature stabilization before engaging in trauma-focused therapy.