Comparison of spontaneous brain activity in distinguishing parkinsonian variant of multiple system atrophy from Parkinson’s disease at an early stage

BackgroundThe overlapping clinical manifestations in parkinsonian variant of multiple system atrophy (MSA-P) and Parkinson’s Disease (PD) can complicate clinical diagnostic accuracy, particularly in the early stage. The study aims to uncover the patterns of brain function in the initial phase of the two conditions.MethodsWe recruited 24 MSA-P patients, 34 PD patients and 27 healthy controls (HC). Voxel-wise fractional amplitude of low-frequency fluctuation (fALFF) was compared to characterize regional brain function, followed by seed-based functional connectivity (FC) analysis. Receiver operating characteristic (ROC) analyses were used to examine the diagnostic accuracy of fALFF.ResultsCompared to HC, decreased fALFF was observed in the bilateral basal ganglia (BG) of MSA-P patients, while decreased fALFF was identified in the left BG of PD patients. Additionally, elevated fALFF was found in the superior cerebellum for MSA-P patients and the temporo-occipital cortex for PD patients. Furthermore, PD patients exhibited increased FC in the cortico-striatal loop compared to MSA-P patients. The fALFF of the left caudate distinguished MSA-P from HC with an area under the curve (AUC) of 0.838 (p