Differentiating between intrapsychic symptoms and behavioral expressions ofborderline personality disorder in relation to childhood emotionalmaltreatment and emotion dysregulation: an exploratory investigation

Background: Borderline personality disorder (BPD) is a severe mental disorder, characterized by pronounced instability in emotions, self-image, and interpersonal relationships. Experiences of childhood maltreatment are among the risk factors for BPD. While self-damaging and aggressive acts often occur, not every person with the disorder shows markedly dysregulated behaviour. Internalized symptoms, such as shame, loneliness, and self-disgust tend to be more pervasive and persist after clinical remission.Objective: Here we investigated associations between BPD symptom severity, childhood maltreatment, and emotion regulation difficulties. We further explored if the Borderline Symptom List (BSL) could potentially be used to differentiate between internalized symptoms (intrapsychic strain) and externalized symptoms (dysregulated behaviours) in future research.Method: 187 women with at least mild BPD symptoms (65% having a diagnosis of BPD) completed the BSL 23 including its 11-item supplement (BSL-S), the Childhood Trauma Questionnaire (CTQ), and Difficulties in Emotion Regulation Scale (DERS). Participants further underwent a semi-structured clinical interview to assess BPD criteria (International Personality Disorder Examination, IPDE). Multivariate models and regression-based bootstrapping analyses were performed to test direct and indirect effects.Results: Childhood trauma severity, especially emotional abuse, positively predicted BPD symptom severity. A significant indirect effect through emotion regulation difficulties was found (k2=.56). When exploring associations with BPD criteria (IPDE), the BSL-23 mean significantly correlated with separation anxiety, identity and mood problems, chronic emptiness, suicidal ideation, and dissociation, while the BSL-S correlated with self-harming impulsive behaviour and anger outbursts.Conclusions: Findings complement previous research, highlighting the role of childhood maltreatment and emotion regulation difficulties in BPD. While our findings need to be seen as preliminary and interpreted with caution, they suggest that the BSL may be used to differentiate between internalized symptoms and behavioural expressions of BPD in future research. Such a distinction might help to deepen the understanding of this complex heterogenous disorder.