MAPT and Parkinson disease: Several studies focusing on the biological and physiological correlations between α-Syn and tau have noted that (i) polymorphisms of α-Syn and tau are commonly associated with sporadic PD [35, 36] and that (ii) α-Syn and tau are colocalized in the same proteinaceous aggregates in some synucleinopathies and tauopathies, such as PD with dementia (PDD), DLB, and Lewy body variant of AD (LBVAD) [1, 37, 38].