Aberrant resting-state functional networks in depression

Numerous resting-state functional magnetic resonance imaging studies have revealed that major depressive disorder (MDD) is associated with abnormal functional connectivity (FC) within and between large-scale functional networks such as the default mode network (DMN), cognitive control network (CCN) and affective network (AN). Compared with healthy controls, individuals with MDD usually show (i) increased FC within the anterior DMN and decreased FC within the posterior DMN, (ii) decreased FC within the CCN and (iii) increased FC within limbic system and decreased FC in the reward system in the AN. Depression related interactive changes between networks have also been reported: (i) decreased FC between DMN and CCN, (ii) increased FC between DMN and AN, and (iii) decreased FC between CCN and AN. These findings on network interaction may represent impaired resource allocation and information integration in MDD. Major weakness in the present rfMRI studies of depression resides in small sample and lack of multidimensional features. Meanwhile, as several brain disorders may show commonly disrupted functional architectures, depression-related specific alterations are typically lacking. We suggest that future studies may advance by combining multidimensional big data and individualized characterization, as well as examining shared and distinct functional network mechanisms of MDD in the spectrum of psychiatric disorders.