Alzheimer's disease (AD) is characterized by progressive cognitive decline along with neuropsychiatric symptoms including depression and psychosis. Depression is a common psychiatric disorder occurring in people across the lifespan. Accumulating evidence indicates that depression may be a prodrome and/or a "risk factor" for AD. However, whether AD and depression share a common pathophysiological pathway is still unclear. The aim of this study was to identify regional alterations in brain function associated with depressive symptoms in mild AD patients. Thirty-two mild AD patients were evaluated using the Neuropsychiatric Inventory and Hamilton Depression Rating Scale, and were divided into two groups: 15 AD patients with depressive symptoms (D-AD) and 17 non-depressed AD (nD-AD) patients. Using the approach of regional homogeneity (ReHo), we characterized resting-state regional brain activity in D-AD and nD-AD patients. Compared with nD-AD patients, D-AD patients showed decreased ReHo in the right precentral gyrus, right superior frontal gyrus, right middle frontal gyrus, and right inferior frontal cortex. Our findings show regional brain activity alterations in D-AD patients. Thus, D-AD pathogenesis may be attributed to abnormal neural activity in multiple brain regions.
Keywords: Alzheimer’s disease; depressive symptoms; regional homogeneity; resting state functional magnetic resonance imaging.