Resting-state functional connectivity reveals cortical compensatory reorganization in idiopathic REM sleep behavior disorder without hyposmia.
Resting-state functional connectivity reveals cortical compensatory reorganization in idiopathic REM sleep behavior disorder without hyposmia.
A plain-language reading has not been prepared for this paper yet.
Original abstract
OBJECTIVE: Idiopathic REM sleep behavior disorder (iRBD) is a well-established prodromal manifestation of α-synucleinopathies, and patients without hyposmia may represent an early stage of the "body-first" Parkinson's disease (PD) subtype. This study aimed to investigate brain functional network alterations in hyposmia-free iRBD patients and validate the hypothesis of early cortical compensatory mechanisms. METHODS: Data were retrieved from the Parkinson's Progression Markers Initiative (PPMI) database. Thirty-seven hyposmia-free iRBD patients and 37 demographically matched healthy controls (HCs) were included. Degree centrality (DC) analysis to identify functional hub alterations, and seed-based functional connectivity (FC) analysis using differentially expressed DC regions as regions of interest. RESULTS: Compared with HCs, iRBD patients exhibited significantly increased DC values in the left superior frontal gyrus. Seed-based FC analysis revealed enhanced connectivity between the Frontal_Sup_2_L and multiple cortical regions, including prefrontal subregions, temporal gyri, and sensorimotor areas. Within the iRBD group, the mean FC strength between the Frontal_Sup_2_L and its differentially connected brain regions was negatively correlated with RBDSQ scores (r = -0.360, p = 0.029). CONCLUSIONS: Our findings suggest that hyposmia-free iRBD patients exhibit compensatory reorganization of brain functional networks centered on the left superior frontal gyrus, supporting the early cortical compensation hypothesis in the "body-first" α-synucleinopathy subtype. Stratification by both the presence and timing of hyposmia relative to RBD onset is critical for reconciling inconsistent rs-fMRI findings in iRBD.The DC value of the left Frontal_Sup_2_L and its FC with extensive cortical regions represent candidate imaging indicators for prodromal α-synucleinopathies, whose clinical utility requires prospective validation in larger independent cohorts with longitudinal designs.