Decreased interhemispheric coordination in the posterior default-mode network and visual regions as trait alterations...

Decreased homotopic connectivity has been implicated in the neurophysiology of major depressive disorder (MDD) with inconsistent findings. A combination of clinical and methodological variabilities may account for the inconsistency, and thus limiting the reproducibility of the findings. The present study aims to examine voxel-mirrored homotopic connectivity (VMHC) alterations in two independent samples of patients with first-episode, drug-naive MDD. The samples included 59 patients and 31 controls from Sample 1 and 29 patients and 24 controls from Sample 2. VMHC was evaluated in both samples with an overlapping technique, which was used to define regions of abnormality common to both samples. Moreover, receiver operating characteristic curve and support vector machine were employed to differentiate the patients from the controls in both samples. Compared with the controls, the patients in both samples exhibited decreased VMHC in overlapped brain clusters, including the posterior cingulate cortex (PCC) and cuneus. Moreover, the VMHC values in the PCC and cuneus and a combination of the VMHC values in these two clusters could robustly discriminate between patients and controls with good sensitivities and specificities in both samples. This study is the first to examine VMHC abnormalities in first-episode, drug-naive patients with MDD in two independent samples by using an overlapped technique. The patients exhibit decreased VMHC in overlapping clusters in the posterior default-mode network and visual regions, which may be trait alterations for MDD. The present study provides a new perspective for understanding the neurophysiologic abnormalities of VMHC in MDD.