Exploring Transdiagnostic Mechanisms Linking Borderline Personality Disorder and Disordered Eating.

Borderline personality disorder (BPD) frequently co-occurs with eating disorders (EDs). Disordered eating may serve as a coping strategy to regulate emotions/manage rejection sensitivity, abandonment fears, shame, and self-disgust. Research examining disordered eating in BPD remains limited. This study explored ED pathology/related psychological constructs in adults diagnosed with BPD. Eighty participants completed questionnaires assessing BPD symptom severity, ED pathology, childhood trauma, cognitive distortions, shame, self-disgust, coping, personality traits, and emotion regulation. Mean-centered linear regression models tested whether psychological constructs influenced the association between BPD severity (BSL-95) and disordered eating (EDI-2, EDE-Q). Given the sample size, moderation analyses were considered exploratory. BSL-95 was associated with disordered eating (p < .001), consistently across EDI-2 but less robustly for EDE-Q. Two exploratory interactions emerged: person-related self-loathing strengthened the BSL-95-EDE-Q link, and agreeableness was associated with variation in the BSL-95-EDI-2 association. Findings underscore BPD-ED associations/highlight transdiagnostic vulnerabilities; however, interaction findings should be interpreted with caution due to the study's exploratory nature.