Longitudinal Trajectory of Borderline Symptoms and Associated Problematic Behaviors Throughout a Standard 12-Month Dialectical Behavior Therapy in Adults With Borderline Personality Disorder

A large body of research supports the efficacy of dialectical behavior therapy (DBT) for the treatment of borderline personality disorder (BPD). This study examined the trajectory of symptomatology change throughout a 12-month BPD intervention in 152 outpatients with BPD who experienced active suicidal ideation. Borderline symptoms were assessed weekly by therapists and every 3 months by outpatients. Analyses of linear mixed-effects models revealed a significant effect of intervention on reducing the frequency of BPD-related behaviors evaluated by both therapists and outpatients. Completers exhibited continuous reductions in symptomatology across treatment, with a tipping point between the sixth and ninth months. Reduced symptomatology was particularly pronounced for self-harm, suicidal threat, suicidal ideation, binge eating, risky behavior, and anger outbursts. However, addictive behaviors were more resistant to change over time. These findings open new avenues for further understanding of the mechanisms of change underpinning psychotherapy treatment for BPD and shed light on potential treatment-resistant BPD symptoms.