Objective: To determine the effect of cerebellar atrophy on resting-state network abnormalities in individuals with Parkinson’s disease.

Background: In Parkinson’s disease, the cerebellum is a seat of both pathological change and functional compensation. Given the cerebellar connectivity with much of the cortex and its role in all aspects of behaviour, these abnormalities in Parkinson’s disease can potentially have widespread effects on motor and non-motor symptoms. Yet the relationship between pathological change and functional compensation in the cerebellum is not well understood.

Methods: We examined how atrophic change in the cerebellum impacts functional connectivity patterns within the cerebellum and between cerebellar-cortical networks. In 42 Parkinson’s disease patients and 29 controls, voxel-based morphometry confirmed grey matter loss across the motor and cognitive cerebellar territories in the patient cohort.

Results: The extent of cerebellar atrophy was correlated with decreased resting-state connectivity between the cerebellum and large-scale cortical networks, including the sensorimotor, dorsal attention and default networks. The severity of patients’ motor impairment was predicted by a combination of atrophy and decreased cerebellar-sensorimotor connectivity. In contrast, cerebellar atrophy was correlated with increased connectivity between the cerebellum and frontoparietal network. A post-hoc analysis exploring the effect of atrophy in subthalamic nucleus, a cerebellar input source, confirmed that a significant negative relationship between grey matter volume and intrinsic cerebellar connectivity seen in controls was absent in the patients.

Conclusions: These findings demonstrate that cerebellar atrophy is related to both increases and decreases in cerebellar-cortical connectivity, suggesting that local cerebellar atrophy influences the capacity for pathologic versus compensatory changes. Our post-hoc analysis demonstrates that a modulatory relationship between the subthalamic nucleus and intra-cerebellar connectivity is lost in Parkinson’s disease, which may contribute to pathological activation within the cerebellum. The results further confirm a critical role for the cerebellum in Parkinson’s disease and reveal the contribution of local atrophic change in determining functional connectivity patterns.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/cerebellar-atrophy-in-parkinsons-disease-and-its-implication-for-network-connectivity/