Dual tasking (DT) impairments in Parkinson disease (PD) are a correlate of fall risk. Their biological basis may reflect multiple underlying pathological causes.

In a cross-sectional cohort of 20 participants with PD, we explored the association between Abeta plaque burden and dual task cost (DTC) on the timed up and go test (TUG). TUG gait parameters were assessed using Ambulatory Parkinson’s disease monitoring (APDM) OPAL wearable sensors. Baseline TUG testing was followed by TUG testing during which the participant performed a cognitive task. DTC was calculated as the percentage difference in seconds between the two tasks. Regional Abeta plaque burden was assessed by [11C]Pittsburgh compound B (PiB) positron emission tomography (PET) imaging. Bivariate Pearson’s r statistic was calculated between DTC and PiB distribution volume ratio (DVR) in different regions of interest.

DTC during the TUG show no significant correlations with PiB DVR in the total cortical mantle (r=0.061, p=0.797), visuospatial cortex (r=0.061, p=0.798), striatum (r=0.033, p=0.890), or thalamus (r=0.041, p=0.865) but did correlate with elevated PiB DVR in the substantia nigra (r=0.535, p=0.015).

DTC in PD does not correlate with supratentorial amyloid plaque burden but may reflect mixed neurodegenerative pathology, including Abeta plaque burden, in the substantia nigra.