Disrupted white matter integrity in first-episode, drug-naive, late-onset depression

Abnormalities of white matter integrity in frontal and limbic regions have been postulated to play a key role in the pathophysiology of geriatric depression. However, there is no diffusion tensor imaging (DTI) study in patients with first-episode, drug-naive, late-onset depression (LOD). The aim of this study was to investigate whole-brain fractional anisotropy (FA) difference between patients with LOD and healthy controls without a previously determined region of interest.

The sample included 15 patients with first-episode, drug-naive LOD and 15 age-, sex-, and education-matched healthy controls. The tract-based spatial statistics (TBSS) method was employed to analyze the DTI data.

Lower FA in the white matter of bilateral parahippocampal gyrus was observed in patients with LOD relative to healthy controls by voxel-wise statistics with the TBSS method. Patients did not have higher FA values in any brain regions compared to healthy controls. There was no correlation between the abnormal FA value in bilateral parahippocampal gyrus and depression severity or related factors.

The present study should be considered preliminary due to relatively small sample size.

Our findings suggest that loss of white matter integrity in parahippocampal gyrus may be associated with the pathophysiology of LOD, and thus highlight the limbic contribution to the pathophysiology of LOD.