Alterations in regional homogeneity of resting state brain activity in Parkinson′s disease patients with depression

Objective To investigate the changes of regional homogeneity (ReHo) in Parkinson′s disease (PD) patients with depression and their relationship with major depressive disorder. Methods A total of 42 PD patients without depression, 20 PD patients with depression, 20 major depressive disorder patients and 47 well-matched healthy controls were scanned with resting-state functional magnetic resonance imaging for ReHo analysis. The Hamilton Depression Scale (HAMD), Unified Parkinson′s Disease Rating Scale (UPDRS-Ⅲ) and Hoehn-Yahr stage were used to assess the clinical symptoms, then the correlations between abnormal brain regions and clinical data were explored. Results (1) The main effect of Parkinson′s disease: PD group showed higher ReHo in left ventrolateral prefrontal cortex and right precuneus, but lower ReHo in bilateral supplementary motor area and left angular gyrus. (2) The main effect of depression: The depression group had increased ReHo in bilateral cerebellum, and decreased ReHo in bilateral precentral gyrus, postcentral gyrus, left inferior frontal gyrus, left posterior cingulate gyrus, left supplementary motor area, right dorsolateral prefrontal cortex, right inferior parietal gyrus and right calcarine. (3) Interactive effect of PD and depression: Interactive brain areas included bilateral middle frontal gyrus, left inferior frontal cortex and supramarginal gyrus. (4) The ReHo of the brain regions under main effect of depression including right dorsolateral prefrontal cortex (r=-0.526, P<0.01) and right inferior parietal gyrus (r=-0.456, P<0.01) had significant negative correlation with HAMD scores. Conclusion PD patients with depression have abnormal brain function, and PD with depression is not simply an overlay of PD and major depressive disorder. Key words: Parkinson disease; Depression; Resting state; Magnetic resonance imaging; Regional homogeneity