Unveiling the neural network of freezing of gait in Parkinson's disease: A coordinate-based network study.

BackgroundFreezing of gait (FoG) is a debilitating symptom in Parkinson's disease (PD), yet its pathophysiological mechanisms remain poorly understood. Several studies have investigated the FoG neuroimaging correlates, with heterogeneous results.ObjectiveThis study investigated in a large PD cohort whether the disparate neuroimaging findings may converge to a common brain network.MethodsT1-weighted MRI scans of 500 PD patients (90 with FoG [PD-FoG] and 410 without FoG [PD-nFoG]) were acquired from the Parkinson's Progression Markers Initiative. A voxel-based morphometry (VBM) analysis was conducted to identify clusters of decreased grey matter (GM) in PD-FoG patients. Subsequently, VBM coordinates of significant clusters were used as seed regions to generate connectivity network maps using a large functional normative connectome, and these maps were overlapped to identify regions connected with most VBM clusters.ResultsPD-FoG patients showed GM atrophy in cerebellar lobes, hippocampus, putamen, insula, inferior temporal gyrus and lateral orbitofrontal gyrus compared with PD-nFoG patients. Network analysis revealed that these regions colocalized within a specific brain network focused on midbrain, substantia nigra, subthalamic nucleus, globus pallidus, inferior putamen and dorsal medial cerebellum. These findings were confirmed by using coordinates from previous VBM studies for the network analysis, validating our results.ConclusionsThis study revealed a brain network underlying FoG in PD, reducing the heterogeneity of previous neuroimaging evidence on FoG. These results may represent a significant step forward in the understanding of FoG and may be relevant for optimized targeted neuro-modulatory treatments to reduce FoG in PD patients.