Altered Localand Matrix Functional Connectivity In Depressed Essential Tremor

Background: Depression in essential tremor(ET)has been constantly studied and reported,while the associated brain activity changes remain unclear.Recently,regional homogeneity(Re Ho),a voxel-wise local functional connectivity(FC)analysis of resting-state functional magnetic resonance imaging,has provided a promising way to observe spontaneous brain activity.Methods: Local FC analyses were performed in forty-one depressed ET patients,49 non-depressed ET patients and 43 healthy controls(HCs),and then matrix FC and clinical depression severity correlation analyses were further performed to reveal spontaneous neural activity changes in depressed ET patients.Results: Compared with the non-depressed ET patients,the depressed ET patients showed decreased Re Ho in the bilateral cerebellum lobules IX,and increased Re Ho in the bilateral anterior cingulate cortices and middle prefrontal cortices.Twenty-five significant changes of Re Ho clusters were observed in the depressed ET patients compared with the HCs,and matrix FC analysis further revealed that inter-ROI FC differences were also observed in the frontal-cerebellar-anterior cingulate cortex pathway.Correlation analyses showed that clinical depression severity was positively correlated with the inter-ROI FC values between the anterior cingulate cortex and bilateral middle prefrontal cortices and was negatively correlated with the inter-ROI FC values of the anterior cingulate cortex and bilateral cerebellum lobules IX.Conclusion: Our findings revealed local and inter-ROI FC differences in frontal-cerebellar-anterior cingulate cortex circuits in depressed ET patients,and among these regions,the cerebellum lobules IX,middle prefrontal cortices and anterior cingulate cortices could function as pathogenic structures underlying depression in ET patients.