BACKGROUNDBorderline personality disorder (BPD) is linked to impairments in white matter (WM) integrity, with traumatic experiences (TE) playing a key role in its development. As TE can affect brain structure, this study examined the parietal-prefrontal WM pathway, focusing on the superior longitudinal fasciculus (SLF), the longest association bundle, to explore WM integrity impairments and their link to BPD symptoms.METHODOLOGYThe study included 90 women (47 with BPD, 43 healthy controls). Participants underwent psychopathology assessments and diffusion tensor imaging (DTI) to measure WM integrity. Mean fractional anisotropy (FA) values were calculated for SLF subdivisions (SLF I, II, III). BPD symptoms were evaluated using the Five-Factor Borderline Inventory.RESULTSHealthy controls showed significantly higher FA in the left SLF I and a trend toward higher FA in the left SLF III compared to BPD. Left SLF I FA mediated the link between trauma (e.g., sexual harassment, emotional/physical abuse) and BPD symptoms (despondence, fragility). Left SLF III FA mediated the relationship between sexual harassment and anxious uncertainty.CONCLUSIONThe SLF mediates the impact of TE on anxiety and depression in BPD, highlighting neurobiological mechanisms and potential research directions.