Distinct and shared mentalizing patterns in borderline personality disorder and somatic symptom and related disorders

Objective Mentalizing impairments have been documented in borderline personality disorder (BPD) and somatic symptom and related disorders (SSRD), yet direct comparisons remain rare. This cross-sectional case-control study compared mentalizing patterns among individuals with BPD (n = 37), SSRD (n = 40), and community controls (n = 37). Methods Task-based and self-report measures assessed uncertainty about mental states, mentalizing across relational contexts, self- and other-mentalizing, mentalized affectivity, and related constructs (empathy, theory of mind, attachment, interpersonal functioning).Results Both clinical groups demonstrated greater impairment than controls in uncertainty about mental states, processing emotions, and mentalizing across relational contexts; empathy and theory of mind did not differ from controls. BPD showed greater impairment than SSRD in uncertainty about mental states and emotion processing, but not in mentalizing across relational contexts (Mentalizing Vignettes Task-24). Self-mentalizing was lower than controls in BPD only. SSRD showed impairments in processing, but not in identification of emotions, contrary to prior accounts of broad emotional-awareness deficits.Conclusion Mentalizing difficulties in both clinical groups were most apparent in uncertainty about mental states, emotional processing, and mentalizing within relational contexts. Disorder-specific patterns (self-mentalizing in BPD and emotional processing in SSRD) may inform assessment and intervention research.