Regional cerebral cholinergic vesicular transporter correlates of visual contrast sensitivity in Parkinson's disease: Implications for visual and cognitive function

Visual and visual processing deficits are implicated in freezing, falling, and cognitive impairments in Parkinson's disease (PD). In particular, contrast sensitivity deficits are common and may be related to cognitive impairment in PD. While dopaminergic deficits play a role in PD-related visual dysfunction, brain cholinergic systems also modulate many aspects of visual processing. The aim of this study was to explore regional cerebral cholinergic terminal density correlates of contrast sensitivity in PD. Ninety-one PD subjects underwent contrast sensitivity testing, motor testing, cognitive testing, and brain MRI and [¹⁸F]-fluoroethoxybenzovesamicol [¹⁸F]-FEOBV PET imaging. Whole brain false discovery error-corrected (p < 0.05) correlations revealed significant associations between VAChT deficits in pericentral, limbic, and visual processing regions and contrast sensitivity performance, independent of disease duration and dopaminergic medication doses. These results suggest that brain cholinergic deficits correlate with contrast sensitivity deficits in PD. Additionally, decreased Rabin contrast sensitivity scores were associated with lower total scores in the Parkinson's Disease Cognitive Rating Scale. These findings suggest that diminished cognitive performance correlated with contrast sensitivity partly reflects underlying vulnerabilities of brain cholinergic systems.