Objective: To investigate the cortical/subcortical grey matter (GM) changes and network functional alterations in PD-FoG patients, in PD developing FoG (PD-FoG-converters) and PD not developing FoG (PD-non-converters) over one and two years of follow-up.

Background: Currently, no longitudinal studies have investigated the clinical and structural/functional MRI correlates of FoG and FoG conversion over time.

Method: Thirty PD-FoG, 11 PD-FoG-converters and 11 PD-non-converters matched for age, sex, education, disease duration and disease severity were recruited and followed up for two years. A sample of 30 healthy controls (HC) matched for age, sex and education was included at baseline. All subjects underwent clinical assessment and MRI acquisition to evaluate vertex-by-vertex and regional cortical thickness, basal ganglia (BG) volumes and functional graph metrics alterations at baseline and their changes over two years. A correlation analysis between baseline MRI metrics and clinical worsening overtime in all PD groups was run. A ROC curve was used to investigate if any MRI measures at baseline could differentiate PD-FoG-converters and non-converters over time.

Results: PD-FoG had widespread cortical and BG atrophy at baseline, while PD-FoG-converters and non-converters showed atrophy in sensorimotor areas and BG. Moreover, PD-FoG-converters relative to HC and PD-FoG showed higher local efficiency and clustering coefficient globally and in the parietal lobe at baseline. Over time, PD-FoG showed posterior cingulate atrophy accumulation but stable functional graph metrics. PD-FoG-converters accumulated occipital atrophy and reduced parietal clustering coefficient, while PD-non-converters showed fronto-parietal and temporal atrophy accumulation and increased sensorimotor path length over time. Both structural and functional MRI alterations at baseline correlated with worse executive/attentive functions over time in PD-FoG. The higher parietal clustering coefficient differentiated PD-FoG–converters from PD-non-converters at baseline.

Conclusion: Our results demonstrated that structural MRI is a useful tool to monitor PD progression, while functional MRI is a useful tool to early identify FoG conversion in PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/longitudinal-structural-and-functional-brain-alterations-in-parkinsons-disease-patients-with-freezing-of-gait/