Structural brain features of borderline personality and bipolar disorders

A potential overlap between bipolar disorder (BD) and borderline personality disorder (BPD) has been recently proposed. We aimed to assess similarities and differences of brain structural features in BD and BPD. Twenty-six in-patients with BPD, 14 with BD and 40 age and sex-matched healthy controls (HC) underwent structural magnetic resonance (MR). Voxel-based morphometry analysis with Statistical Parametric Mapping (SPM) was used to localize and quantify gray (GM) and white matter (WM) abnormalities in BD and BPD compared to HC and to identify those specifically affected in each patient group (p<0.001 uncorrected). ROI-based analyses were used as a confirmatory analysis. GM density changes in BD are significantly more diffuse and severe than in BPD as resulting both from SPM and ROI-based analyses. The topography of GM alterations shows some regions of overlap but each disorder showed the involvement of specific regions (involving both cortical and subcortical structures in BD, confined to mainly fronto-limbic regions in BPD). WM density changes are milder in both conditions and involved completely different regions. Although BPD and BD show a considerable overlap of GM changes, the topography of alterations is more consistent with the separate conditions hypothesis and with the vulnerability of separate neural systems.