MR Brain Functional Networks And Structural Changes In Parkinson Disease With REM Sleep Behavior Disorder

Background:Parkinson disease(PD)is a complex degenerative disease of the nervous system.With the problem of population aging becoming more and more serious,PD has caused great burden to the society.It is urgent to find out effective indicators to warn and diagnose disease in the early stages and further explore the pathogenesis of the disease.Many studies showed that PD patients with RBD(PDRBD)tends to be a more severe disease phenotype,meaning a worse prognosis.However,we still know very little about the pathogenesis of PDRBD.Magnetic resonance imaging(MRI)is non-invasive,convenient and sequence-rich,so it has been widely used to explore the pathogenesis of neurodegenerative disease.Materials and Methods:In this study,we collected Parkinson disease patients’ data from PPMI(Parkinson’s Progression Markers Initiative)database and Peking University Shenzhen Hospital.PD patients were divided into the probable RBD group(PD-pRBD)and the unlikely RBD group(PD-npRBD)based on RBD screening questionnaire and RBDQHK respectively.We used graph theory to analyze the functional MRI data of PD and normal control(NC)and used voxel-based morphometry to analyze the corresponding structural MRI data and compared the differences of brain functional network and gray matter volume among PD-pRBD,PD-npRBD and NC.Results:The functional MRI data were analyzed using network analysis method based on graph theory.The study showed that both PD-pRBD and PD-npRBD patients existed small-world characteristics.When compared with the NC group,PD-pRBD patients showed more extensive changes of nodal properties in the neocortex and limbic system than PDnpRBD patients.In addition,when compared with PD-npRBD,PD-pRBD patients showed increased nodal efficiency of the bilateral thalamus(t=2.738,P=0.007;t=2.829,P=0.006)and increased betweenness centrality of the left insula(t=2.810,P=0.006),but decreased betweenness centrality of the right dorsolateral superior frontal gyrus(t=-2.990,P=0.004).The structural MRI data were analyzed using voxel-based morphometry to compare the gray matter volume.The results showed that PD-pRBD patients showed decreased volume of right middle frontal gyrus when compared with PD-npRBD(P<0.001,t=-4.1941).In addition,PD-pRBD patients showed decreased volume of left superior temporal pole(P<0.001,t=-4.8012),left fusiform gyrus(P<0.001,t=-4.1525)and left superior occipital gyrus(P<0.001,t=-3.9188)when compared with NC.And PD-npRBD patients showed decreased volume of left superior temporal pole(P<0.001,t=-4.7033)and increased volume of the left posterior cingulate gyrus(P<0.001,t=3.8037)when compared with NC.Conclusion:Combined with the results of functional network and morphometric analysis,our study provided more imaging basis for that PDRBD may be a more serious phenotype and deepened our understanding of PDRBD and provided a possible target reference for potential modification therapy in the future.