Disrupted rich club organization of white matter networks in de novo Parkinson's disease with REM sleep behavior disorder

Abstract

Introduction: Rapid eye movement (REM) sleep behavior disorder (RBD) is common in Parkinson's disease (PD) but the pathophysiological mechanism is still unclear in PD with RBD. The purpose was to explore the alterations of white matter network topology in de novo PD, with or without RBD.Methods: In total, this study contained 153 de novo individuals with PD and 59 healthy controls recruited from the Parkinson’s Progression Markers Initiative (PPMI) database. In such patients, 56 were probable RBD (PD-pRBD) and 97 were non-probable RBD (PD-npRBD) according to the RBD screening questionnaire (RBDSQ). All the recruited members had diffusion tensor imaging and complete neuropsychological assessments. The structural network of brain and organization of rich club were constructed based on deterministic fiber tracking at the individual level.Results: Compared with PD-npRBD patients, the PD-pRBD patients showed diminished global efficiency and elevated shortest path length. It was found that both the PD-pRBD and PD-npRBD had common hubs including putamen, middle occipital gyrus, precuneus, besides, PD-pRBD mainly recruited additional hubs in the frontotemporal paralimbic regions. Furthermore, the PD-pRBD showed decreased rich-club connections in comparison to PD-npRBD. Additionally, the nodal shortest path length in the right superior frontal gyrus, orbital part (ORBsup.R) was positively correlated to RBDSQ scores in PD-pRBD patients(r=0.25, p=0.01).Conclusions: The results indicated the PD-pRBD patients showed disrupted topological organization of white matter in the whole-brain and rich-club connections which mainly located in frontotemporal paralimbic regions, thus partially helps to illustrate the pathological processes of RBD in PD patients.