White matter microstructural and cognitive function changes in bipolar depression patients with suicidal ideation.

The pathophysiological mechanisms underlying suicidal ideation and decreased cognitive function in bipolar depression remain elusive. This study sought to elucidate the potential neuroanatomical basis of these phenomena using diffusion tensor imaging (DTI). 40 patients experiencing bipolar depressive episodes were enrolled, comprising 20 individuals with suicidal ideation (BDSI +), 20 without suicidal ideation (BDSI-), and 20 healthy controls (HCs), all of whom underwent DTI scanning. Clinical assessments primarily utilized the Beck Scale for Suicide Ideation (BSSI) and the Trail Making Test (TMT). Differences in fractional anisotropy (FA) values among the groups were compared using Tract-Based Spatial Statistics (TBSS). The identified differential brain regions were designated as regions of interest (ROIs), and covariance analysis was employed to compare the FA values among the three groups. Partial correlation analyses were conducted between the FA values in the ROIs and clinical symptoms. Differences in brain regions identified through TBSS were observed in the genu of the corpus callosum and the left anterior corona radiata (p < 0.05). Covariance analysis revealed that the BDSI + group exhibited significantly lower FA values in these regions compared to the HCs (p < 0.05). Partial correlation analyses showed that the FA values in the genu of corpus callosum were negatively correlated with BSSI scores (r = -0.592, p = 0.026) and TMT-A scores (r = -0.642, p = 0.013). The findings from this study suggest that alterations in the connectivity of the genu of the corpus callosum may relate to suicidal ideation and visuospatial function in patients with bipolar depression.