White matter abnormalities in medication-naïve adult patients with major depressive disorder: tract-based spatial...

While increasing evidence suggests that major depressive disorder (MDD) is coincident with the altered white matter microstructure in many brain regions including the prefrontal cortex, parietal lobe, ventral tegmental area and limbic system, it remains controversial in the nature of white matter structural changes and in its relationship with depression syndrome. We believe that the age of patients and the antidepressant treatment to them would contribute to that controversy. Here in this study we explored the microstructural changes of the entire brain white matter of the adult patients with first-episode, antidepressant drug-naïve MDD.

We performed the diffusion tensor imaging (DTI) among a relatively large sample size of patients and age-matched control individuals (forty-one MDD patients and forty-one control subjects) and used recently developed tract-based spatial statistics to analyze the difference of mean fractional anisotropy (FA) between patients and control individuals.

We surprisingly found that MDD patients exhibited a significantly greater mean FA, which is used to elucidate the structural organization of the neural fibers, than control subjects in the whiter matter of the left superior longitufinal fasciculus. However, this change in the white matter of MDD patient did not correlate with depressive clinical features (HMAD, illness duration and initial age) in the present study.

Our data suggest that a potential compensatory regeneration of nerve fibers occurs in the early course of MDD development. Advanced understanding of the potential nerve fiber regeneration in the early course of MDD and its associated mechanisms will possibly shade light on a better strategy for MDD prevention and treatment.