Regional Coherence Changes In Alzheimer’s Disease Patients With Depressive Symptoms:a Resting-state Functional MRI Study

Background Alzheimer’s disease (AD) is characterized by progressive cognitive decline along with various neuropsychiatric symptoms including depression and psychosis. Depression is a common psychiatric disorder affecting individuals across the lifespan. There is accumulating evidence that depression may be a prodrome and/or a "risk factor" for AD. However, it is unclear if AD and depression have common pathophysiological pathways.Objective The aim of this study was to identify regional alterations in brain function associated with depressive symptoms in mild AD patients.Methods Our study included 32 mild AD patients, which met the diagnosis of National Institute on Aging-Alzheimer’s Association workgroups on diagnostic guidelines for Alzheimer’s disease criteria. The patients were evaluated using the Neuropsychiatric Inventory and Hamilton Depression Rating Scale and were further 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.Results D-AD and nD-AD groups were well matched with regards age (t=-1.564, P =0.128), gender distribution (χ2=0.161, P=0.735), and years of education (t=0.211, P=0.835). There was a significant difference in HAMD score between the two groups (t=14.872, P<0.001). Compared with nD-AD patients, D-AD patients showed decreased ReHo in the right precentral gyrus, right superior frontal gyrus (SFG), right middle frontal gyrus (MFG), and right inferior frontal cortex (IFC).Conclusions 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.