Neural correlates of severity in major depressive disorder: A combined structural and resting-state functional MRI study

Major depressive disorder (MDD) is a disabling and severe psychiatric disorder with high risk of suicide, and adulthood is one of the most probable period for the onset. The neural basis underlying the young adults with MDD remains underexplored. In this study, we have investigated the cortical and subcortical alterations of neuroanatomical structures and functional activation in twenty-three young depressive patients with suicide attempt versus forty-five healthy controls. Significant disruptions of regional gray matter volume at left middle frontal extending to superior frontal involved with cognitive processing were found correlated with anxiety scores in MDD patients. Increased cortical thickness at right orbital frontal responsible for decision making was correlated with severity of suicide. Further, increased functional activation at left auditory association cortex was a hallmark of hallucinations in MDD, which was directly associated with depression severity. Moreover, decreased spontaneous brain activity at right inferior frontal was also found, reflecting lower inhibition control in MDD patients. The abnormal structural and functional findings at fronto-cortical areas implied the dysfunctional cognitive control and emotion regulation in MDD. The alterations correlated with clinical scores might indicate the reliable neural markers for MDD.