Structural white matter alterations in borderline personality disorder: A narrative review and methodological considerations.

Borderline personality disorder (BPD) is a severe and heterogeneous psychiatric condition characterized by emotional dysregulation, impulsivity, and interpersonal instability. Increasing evidence suggests that disruptions in white matter (WM) microstructure may contribute to its neurobiological underpinnings. Clarifying these findings is important because diffusion MRI studies in BPD remain heterogeneous in terms of age, symptom severity, comorbidity, medication status, trauma exposure, and analytic approach. This narrative review synthesizes current findings from diffusion tensor imaging (DTI) studies examining WM alterations in individuals with BPD and discusses key methodological considerations that influence the interpretation of results. Across studies, the most consistent abnormalities were observed in the corpus callosum, particularly the genu and body, which may reflect altered interhemispheric connectivity. Additional alterations were reported in fronto-limbic pathways, including the cingulum and fornix, as well as long association tracts such as the superior and inferior longitudinal fasciculi. These findings are consistent with the hypothesis that WM alterations in BPD may extend across large-scale structural networks that are anatomically connected to emotional and cognitive systems. However, results remain heterogeneous due to methodological variability, small sample sizes, and clinical heterogeneity. Differences in imaging techniques and analytical approaches further complicate comparisons across studies. Overall, WM alterations may represent one component of the neurobiological profile of BPD; however, their functional and clinical significance requires confirmation using advanced diffusion methods, longitudinal designs, and standardized protocols.