Moreover, Vijayaraghavan et al. (2014) observed in their combined sample of APOE4 carriers (PD-NC, PD-MCI, PDD, and DLB) to have higher amyloid-beta (assessed via [11C]-PiB retention) in their striatal and cortical regions, as well as a lower MMSE score when compared to non-carriers (Vijayaraghavan et al., 2014). Here, APOE is linked to Parkinson disease.