Self-Other Mentalizing and Attachment Insecurity in the Dimensional Model of Personality Disorders: From Research to...

Research on different aspects of mentalizing is essential for understanding the mechanisms underlying personality disorders (PDs) and for informing psychotherapy approaches, in which mentalizing is considered a key mechanism of change. This study aimed to explore whether self- and other-mentalizing, in interaction with attachment insecurity, differentially explain Criteria A (level of personality functioning) and B (maladaptive traits) of the Alternative Model for Personality Disorders in the DSM-5. Our sample consisted of 109 participants (54% female, 41% male and 5% nonbinary). We used the Structured Clinical Interview for DSM-5 Personality Disorders, a Movie for the Assessment of Social Cognition, the Reflective Functioning Questionnaire, the Experiences in Close Relationships-Revised, the Self and Interpersonal Functioning Scale and the Personality Inventory for DSM-5. Regression analyses show that self-mentalizing deficits uniquely predict both Criterion A domains (self and interpersonal functioning) and all five maladaptive traits, while other-mentalizing is relevant only to interpersonal functioning. Explained variance (adjusted R²) ranges from 55% to 18%. Additionally, mentalization moderates the relationship between insecure attachment and personality pathology (interpersonal functioning, Negative Affectivity and Detachment), mainly with greater mentalization deficits linked to more severe personality dysfunction under heightened attachment insecurity. Our findings authorize mentalizing as a crucial factor in PD, supporting the potential value of mentalization-focused interventions in addressing both the severity and the 'flavour' of PD. Notably, our findings suggest a hierarchy within self- and other-mentalizing, indicating that self- mentalizing plays a more foundational role in PD. Through a comprehensive, multimethod assessment of mentalization, this study offers a refined understanding of its role in psychopathology, providing valuable insights that could guide the development of more targeted therapeutic interventions.