Investigating the Relationship Between Defense Mechanisms and the Therapeutic Alliance in Dialectical Behaviour Therapy for Borderline Personality Disorder

Abstract

Defenses play an important role in psychotherapy, as clients' overall defensive functioning (ODF) predicts treatment outcomes. Defensive functioning may influence the relationship between the therapeutic alliance and outcome; however, findings are mixed. This study examined the relationship between defensive functioning, alliance rupture and repair, and outcomes in dialectical behaviour therapy (DBT) for borderline personality disorder (BPD), using secondary data from the FASTER study. In a subsample of 60 participants, observers coded session 6 using the Defense Mechanism Rating Scale (DMRS) and Rupture Resolution Rating System (3RS). Post-treatment outcomes were measured using the Borderline Symptom List (BSL-23) and Symptom Checklist-90-Revised (SCL-90-R). Partial correlations showed lower ODF was associated with greater rupture salience, specifically withdrawal ruptures. Regression analyses revealed ODF moderated the relationship between rupture salience and repair effectiveness, and mature defenses moderated the relationship between rupture salience and outcomes. Findings suggest, without mature defenses, therapists may struggle to resolve ruptures effectively.