Alterations of voxel‐wise spontaneous activity and corresponding brain functional networks in multiple system atrophy patients with mild cognitive impairment

Emerging evidence has indicated that cognitive impairment is an underrecognized feature of multiple system atrophy (MSA). Mild cognitive impairment (MCI) is related to a high risk of dementia. However, the mechanism underlying MCI in MSA remains controversial. In this study, we conducted the amplitude of low‐frequency fluctuation (ALFF) and seed‐based functional connectivity (FC) analyses to detect the characteristics of local neural activity and corresponding network alterations in MSA patients with MCI (MSA‐MCI). We enrolled 80 probable MSA patients classified as cognitively normal (MSA‐NC, n = 36) and MSA‐MCI (n = 44) and 40 healthy controls. Compared with MSA‐NC, MSA‐MCI exhibited decreased ALFF in the right dorsal lateral prefrontal cortex (RDLPFC) and increased ALFF in the right cerebellar lobule IX and lobule IV–V. In the secondary FC analyses, decreased FC in the left inferior parietal lobe (IPL) was observed when we set the RDLPFC as the seed region. Decreased FC in the bilateral cuneus, left precuneus, and left IPL and increased FC in the right middle temporal gyrus were shown when we set the right cerebellar lobule IX as the seed region. Furthermore, FC of DLPFC‐IPL and cerebello‐cerebral circuit, as well as ALFF alterations, were significantly correlated with Montreal Cognitive Assessment scores in MSA patients. We also employed whole‐brain voxel‐based morphometry analysis, but no gray matter atrophy was detected between the patient subgroups. Our findings indicate that altered spontaneous activity in the DLPFC and the cerebellum and disrupted DLPFC‐IPL, cerebello‐cerebral networks are possible biomarkers of early cognitive decline in MSA patients. Our results suggest that the deactivation in the dorsal lateral prefrontal cortex (DLPFC) and activation in the cerebellum, and DLPFC‐inferior parietal lobe, cerebello‐default mode network disruptions are possible biomarkers of mild cognitive impairment (MCI) in multiple system atrophy (MSA) patients. Early cognitive decline in MSA is more dependent on functional disruptions than on morphological changes. Our findings provide a novel insight for further understanding the neuromechanism underlying MCI in MSA patients.