Adolescents' Pathological Personality Traits and Mentalization in Daily Social Interactions: Linking Criterion A and B from the DSM-5 AMPD

Personality pathology presents unique challenges in adolescence, a critical period for developing social autonomy and complex peer relationships. Yet, little research examines how these vulnerabilities unfold in daily life. This preregistered, multi-informant ambulatory assessment (AA) study tracked 294 adolescents (58.5% female) aged 12–21, capturing 13,190 interactions over 14 days. Using Contemporary Interpersonal Theory and the DSM-5 Alternative Model for Personality Disorders (AMPD), we modeled links between personality pathology, perceptions of others’ and participants’ interpersonal behavior, and mentalizing. Multilevel structural equation modeling (MSEM) revealed that personality pathology was associated with lower daily social satisfaction in youth. Self-reports linked pathology to reduced perceived and enacted warmth, higher perceived and enacted dominance, and greater variability in all these processes, with informant reports showing similar but weaker patterns. Contrary to expectations, personality pathology was not associated with lower average mentalization but predicted greater fluctuations in mentalizing across interactions. Higher pathology strengthened the link between mentalizing and enacted dominance, driven by Antagonism, while Psychoticism showed the reverse pattern, weakening this association. Detachment reduced the association of mentalizing and perceived warmth, and negative affectivity weakened the link between mentalizing and enacted dominance. Findings highlight the dynamic nature of interpersonal dysfunction in adolescent personality pathology. Recognizing maladaptive patterns early may guide interventions that stabilize social interactions and promote mentalizing in ways that foster connection rather than control, reducing long-term challenges.