Neurological soft signs in borderline personality disorder and schizophrenia.

Background: Neurological soft signs (NSS) are subtle sensorimotor abnormalities that have been observed in various mental disorders with neurodevelopmental origin. While NSS have been extensively examined in patients with schizophrenia (SZ), preliminary evidence also suggests that NSS are also present in patients with borderline personality disorder (BPD). However, a transdiagnostic examination of the severity of NSS in BPD compared to SZ is still lacking.

Methods: Here, NSS were examined with the Heidelberg NSS scale (HNSS) in three groups of female subjects: BPD (n = 45), SZ (n = 30) and healthy controls (HC) (n = 32). Multivariate analysis of variance (MANOVA) was conducted jointly for BPD, SZ, and HC and HNSS subscores. Post hoc tests were performed using linear discriminant analysis (LDA). In the BPD group, partial Spearman correlations (with age and medication as covariates) were performed between NSS scores and depressive symptoms (HAMD-21), impulsivity (BIS-11), dissociative symptoms (DTS), childhood trauma (CTQ), and borderline symptoms (BSL-23).

Results: BPD showed significantly higher NSS levels compared to HCs. For the BPD, significant associations between NSS and childhood trauma and depressive symptoms were found. MANOVA showed a significant group difference, LDA differentiated between HC, and patients with SZ and BPD, but not between the patient groups.

Conclusions: Patients with BPD have significantly higher NSS levels than HC. NSS in BPD showed significant associations with childhood trauma, supporting a "two-hit" model. Importantly, patients with BPD and SZ may show similar NSS patterns, suggesting that sensorimotor dysfunction is a transdiagnostic phenomenon.