Altered white matter integrity in first-episode, treatment-naive young adults with major depressive disorder: A tract-based spatial statistics study

Abstract Because most previous diffusion tensor imaging (DTI) studies have focused on late-life depression, this study examined the possible changes in brain white matter (WM) in first-episode, treatment-naive young adults with major depressive disorder (MDD). DTI was performed in 25 (10 males and 15 females) first-episode, treatment-naive young adult patients with MDD and 25 healthy controls matched for age, gender, and education. A whole-brain statistical comparison method called tract-based spatial statistics (TBSS) was used to analyze the data. Compared with healthy controls, patients with MDD showed decreased fractional anisotropy (FA) values in three WM tracts: the left anterior limb of the internal capsule, the right parahippocampal gyrus, and the left posterior cingulate cortex. Further analysis revealed that FA values in the left anterior limb of the internal capsule were negatively correlated with the severity of depressive symptoms. No regions showed higher FA in MDD patients than in controls. The present results support the hypothesis that altered WM integrity, especially in the cortical–subcortical neural circuit, may contribute to the pathophysiology of MDD. Furthermore, these findings provide novel evidence that microstructural abnormalities in WM may occur early in the course of depression.