Objective: To investigate regional cerebral deposition of β-amyloid in patients with Parkinson’s disease (PD) who have freezing of gait (FoG).

Background: FoG is one of the most debilitating motor impairments in PD. FoG often becomes refractory to dopaminergic medications in advancing PD. Abnormal protein deposits, such as β-amyloid plaques, in neural circuits underlying FoG may provide an explanation for treatment-refractory FoG in PD. Prior cerebral blood flow, glucose metabolic and functional MR neuroimaging studies point to predominant right hemispheric changes in FoG in PD.

Method: In this cross-sectional study, patients with PD (n = 54, 38 male and 16 female, mean age 68.8 ± 6.5 years, Hoehn & Yahr stage 2.67 ± 0.44, Montreal Cognitive Assessment score 25.5 ± 2.5) underwent β-amyloid [¹¹C]PIB PET and UPDRS clinical assessment. PIB-PET images were normalized using the cerebellum grey matter as a reference region. Muller-Gartner partial volume correction method was used to correct the image from the partial volume effect. SPM12 voxel-based independent t-test group comparisons were performed between patients with clinically observed FoG versus those with no evidence of gait freezing.

Results: Ten patients (18.5 %) were observed to have FoG. There was no difference between the groups in terms of age, disease duration and gender between the freezers and non-freezers. The SPM voxel-based t-test showed higher β-amyloid deposition in patients with FoG in a predominant right hemispheric pattern (p<0.05), [figure 1]. Freezers had higher binding in the right temporal lobe (prominently in the lateral temporal cortex and extending into insula with mild uptake in the posterior hippocampus), right orbitofrontal, right more than left prefrontal, right sensorimotor cortex, right more than left superior parietal, right putamen, and right lateral geniculate nucleus and the right more than left cingulum compared to the non-freezers.

Conclusion: Patients with PD and FoG have predominant right hemispheric β-amyloid binding compared to non-freezers. The right hemisphere is dominant for vestibular and the ventral attention network, including visual processing. Disruptions in these neural networks may play a role in the pathophysiology of FoG in PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/right-hemispheric-%ce%b2-amyloid-deposition-associates-with-freezing-of-gait-in-parkinsons-disease/