Patient and therapist perspectives on impact, outcomes and change mechanisms in trauma-focused mentalization-based treatment: a qualitative interview study.

Introduction: Complex trauma is common in individuals with borderline personality disorder (BPD) and linked to persistent difficulties in emotion regulation, self-concept, and relationships. These co-occurring problems often lead to suboptimal outcomes in both trauma- and personality-focused treatments. Trauma-Focused Mentalization-Based Treatment (MBT-TF) is a structured group intervention developed to address complex trauma within a mentalizing framework. This study examined how participants and therapists experienced MBT-TF as an add-on to standard MBT for BPD, focusing on perceived impact, outcomes, and mechanisms of change. Methods: Six participants with BPD and a history of complex trauma and six therapists (two MBT-TF facilitators and four referring MBT therapists) were interviewed following completion of MBT-TF delivered alongside regular MBT. Semi-structured interviews were analyzed using reflexive thematic analysis. Three subsequent focus groups with therapist, participants and experts, refined and validated the emerging themes. Results: Two overarching domains carrying a total of seven themes were defined and validated through the focus groups. The first domain concerned the structured and relational conditions that enabled participants to tolerate the emotional intensity of trauma-focused work and reduce avoidance, grouping four themes: (1) facing emotional intensity together; (2) breaking avoidance in a safe, predictable, and consistent structure; (3) balancing trauma focus versus group dynamics; and (4) collaborative tailoring to individual needs. The second domain captured change processes in MBT-TF, comprising three themes: (5) varying experiences with symptomatic improvement; (6) changing perspectives on self and others through group experience; and (7) generalizing change beyond treatment. Change was mainly experienced as evolving through sharing, and perceiving oneself through the minds of similar others in a safe group context. This was associated with reduced shame, avoidance, and changes in self-other representations. Symptom change and generalization varied across individuals. Discussion: MBT-TF was experienced as tolerable and meaningful, with perceived change aligning with its core conceptual aims, and goals as formulated by participants. Findings suggest MBT-TF may serve as an alternative to or complement symptom-focused trauma treatments. Future research should explore stand-alone delivery, effectiveness, and change processes over time.