This neglects the potential contribution of several other parameters potentially associated with cognitive decline in PD as reviewed in Aarsland, et al. [1], such as genetic subtypes (e.g., mutations in the β-glucocerebrosidase gene, GBA) [47], subtypes regarding the onset of PD (early vs. late) [48], changes in medication (especially anticholinergic drugs) [49, 50], and direct brain imaging correlates. Here, GBA1 is linked to Parkinson disease.