Alterations of white matter integrity in adults with major depressive disorder: a magnetic resonance imaging study.

OBJECTIVE: The purpose of our study was to investigate alterations of white matter integrity in adults with major depressive disorder (MDD) using magnetic resonance imaging (MRI).
METHODS: We performed diffusion tensor imaging with a 3T MRI scanner on 45 patients with major depression and 45 healthy controls matched for age, sex and education. Using a voxel-based analysis, we measured the fractional anisotropy (FA), and we investigated the differences between the patient and control groups. We examined the correlations between the microstructure abnormalities of white matter and symptom severity, age of illness onset and cumulative illness duration, respectively.
RESULTS: We found a significant decrease in FA in the left hemisphere, including the anterior limb of the internal capsule and the inferior parietal portion of the superior longitudinal fasciculus, in patients with MDD compared with healthy controls. Diffusion tensor imaging measures in the left anterior limb of the internal capsule were negatively related to the severity of depressive symptoms, even after we controlled for age and sex.
CONCLUSION: Our findings provide new evidence of microstructural changes of white matter in non-late-onset adult depression. Our results complement those observed in late-life depression and support the hypothesis that the disruption of cortical- subcortical circuit integrity may be involved in the etiology of major depressive disorder.