Short-Term versus Long-Term Mentalization-Based Therapy for Borderline Personality Disorder: A Randomized Clinical Trial (MBT-RCT).

INTRODUCTION: Borderline personality disorder (BPD) is a severe and prevalent psychiatric disorder. Mentalization-based therapy (MBT) is an evidence-based intervention for BPD, and several countries offer treatment programs for BPD lasting for years, which is resource demanding. No previous trial has compared short-term with long-term MBT. OBJECTIVE: The aim of the study was to assess the efficacy and safety of short-term versus long-term MBT for outpatients with BPD. METHODS: Adult outpatients (≥18 years) with subthreshold or diagnosed BPD were randomly assigned (1:1) to short-term MBT (5 months) or long-term MBT (14 months). The primary outcome was BPD symptoms assessed with the Zanarini Rating Scale for Borderline Personality Disorder. Secondary outcomes were functional impairment, quality of life, global functioning, and severe self-harm. All outcomes were primarily assessed at 16 months after randomization. This trial was prospectively registered at ClinicalTrials.gov, NCT03677037. RESULTS: Between October 4, 2018, and December 3, 2020, we randomly assigned 166 participants to short-term MBT (n = 84) or long-term MBT (n = 82). Regression analyses showed no evidence of a difference when assessing BPD symptoms (MD 0.99; 95% CI: -1.06 to 3.03; p = 0.341), level of functioning (MD 1.44; 95% CI: -1.43 to 4.32; p = 0.321), quality of life (MD -0.91; 95% CI: -4.62 to 2.79; p = 0.626), global functioning (MD -2.25; 95% CI: -6.70 to 2.20; p = 0.318), or severe self-harm (RR 1.37; 95% CI: 0.70-2.84; p = 0.335). More participants in the long-term MBT group had a serious adverse event compared with short-term MBT (RR 1.63; 95% CI: 0.94-3.07; p = 0.088), primarily driven by a difference in psychiatric hospitalizations (RR 2.03; 95% CI: 0.99-5.09; p = 0.056). CONCLUSION: Long-term MBT did not lead to lower levels of BPD symptoms, nor did it influence any of the secondary outcomes compared with short-term MBT.

Personality Functioning and Mentalizing in Patients With Subthreshold or Diagnosed Borderline Personality Disorder: Implications for ICD-11.

The 11th revision of the International Classification of Diseases for Mortality and Morbidity Statistics (ICD-11) defines personality disorder according to personality functioning, which relates to self- and interpersonal functioning. The aim of the present study was to assess the relationship between mentalizing and personality functioning in patients with subthreshold or diagnosed borderline personality disorder. A total of 116 eligible participants were included. Mentalizing was assessed using the Mentalization Questionnaire (MZQ), personality functioning (self- and interpersonal functioning) was assessed using the Level of Personality Functioning Scale-Brief Form 2.0 (LPFS-BF), and borderline severity was assessed using the Zanarini Rating Scale (ZAN-BPD). Mediation analysis was employed to test if mentalizing accounted for the relationship between borderline severity and self- and interpersonal functioning. We found a significant relationship between borderline severity and both subscales of the LPFS-BF. Mentalizing fully and significantly mediated the relationship between borderline severity and interpersonal functioning. However, mentalizing only partly mediated the relationship between borderline severity and self-functioning. Controlling for the covariates gender and age did not impact the results. Mentalizing is likely to be involved in the ICD-11 model of personality functioning, especially interpersonal functioning. This could emphasize the relevance of therapy aimed at strengthening mentalizing abilities when treating personality pathology in general and people with borderline personality disorder in particular. However, self-functioning may be more nuanced, as aspects other than mentalizing also influence self-functioning. The study is explorative in nature and has methodological limitations that require caution in the interpretation and generalizability.