Studies evaluating TSPO binding in cognitively impaired PD cases have been limited, but Edison et al. 21 investigated 11C-PK11195 binding in PDD alongside non-demented PD cases and reported increases in temporal, parietal and occipital cortices in both groups compared with controls, with additional involvement of frontal, temporal and cingulate regions in PDD subjects. Here, TSPO is linked to Parkinson disease.