Altered topological properties in PD patients with probable REM sleep behavior disorder through fuctional MRI.

PURPOSE: Rapid eye movement (REM) behavior disorder (RBD) is a common non-motor symptom in Parkinson’s disease (PD) patients. However, its pathogenesis remains unclear. Our study aimed to investigate the topological properties of the functional brain network in PD patients with probable REM sleep behavior disorder (PD-pRBD). METHOD: Using the RBD screening questionnaire, 32 PD patients without RBD (PD-nRBD) and 17 PD-pRBD patients were included. All participants underwent resting-state functional Magnetic Resonance Imaging (rs-fMRI) scan and clinical assessment. We compared the differences between groups in global and nodal topological properties of the brain functional network based on graph theory analysis. Partial correlation analysis was used to estimate the relationship between the significant metrics and clinical scales. RESULTS: The PD-pRBD group showed no significant differences in global topological properties compared to the PD-nRBD group. However, the PD-pRBD group had significantly higher nodal degree centrality in the left cuneus, nodal betweenness centrality in the left putamen and Pallidum, and nodal local efficiency in the left amygdala. They also showed lower nodal local efficiency in the right frontal operculum, inferior frontal gyrus, and left anterior cingulate cortex. Moreover, in the PD-pRBD group, nodal local efficiency in the left anterior cingulate cortex demonstrated a negative correlation with HAMD-24 scores. CONCLUSION: Both PD-pRBD and PD-nRBD patients displayed small-world properties, but PD-pRBD showed more extensive changes of nodal properties than PD-nRBD within the limbic system, basal ganglion, and visual associated regions. These region-specific changes offer crucial insights into the pathophysiological mechanisms of PD comorbid with RBD in brain network analysis.