Exploring the impact of Metacognitive Interpersonal Therapy on borderline personality disorder: a retrospective observational study using a latent transition analysis of symptoms and functional changes over 12 months.

Introduction: Borderline personality disorder (BPD) is marked by emotional instability, interpersonal dysfunction, and high comorbidity, posing significant treatment challenges. Metacognitive Interpersonal Therapy (MIT) targets core features of BPD, including metacognitive impairments and emotional dysregulation. This study uses Latent Transition Analysis (LTA) to assess changes in BPD symptoms and psychological factors over a 12-month MIT intervention, hypothesizing that MIT will reduce symptom severity and improve emotional regulation, metacognitive abilities, and interpersonal functioning.

Methods: This single-center, retrospective observational study included 98 patients, all diagnosed with BPD according to DSM-IV-TR criteria, without severe psychiatric comorbidities or concurrent psychotherapy. These patients underwent a 12-month MIT intervention, delivered in five phases targeting metacognitive and emotional regulation skills. Clinical assessments included SCID-II for BPD diagnosis, SCL-90-R for symptom severity, MAI for metacognitive abilities, and IIP for interpersonal difficulties.

Results: Latent Class Analysis (LCA) identified three baseline profiles: "Affective dysregulation and anger" (14.3%), "Low symptomatic" (7.1%), and "Identity and interpersonal sensitivity" (78.6%). After 12 months of treatment, most participants (58.2%) transitioned to a "Recovered" class, with significant reductions in BPD symptoms. The "Recovered" class showed the greatest improvements in metacognitive abilities, emotional regulation, and interpersonal functioning compared to other groups.

Conclusions: MIT was associated with significant improvements in BPD symptoms, with over half of participants achieving full recovery. These findings suggest that MIT may play a role in enhancing emotional regulation and interpersonal functioning. However, residual symptoms in some participants confirm the complexity of BPD, suggesting the need for further research into long-term outcomes and comorbidities.