MAPT and Parkinsonism: In postmortem studies, the tau protein has been found in Lewy bodies.36 In genomewide associations studies the MAPT gene has been linked to PD, and risk alleles of MAPT have been associated with parkinsonism.37, 38 Furthermore, α‐syn in both mouse and human models has been shown to contribute to the phosphorylation of tau.39, 40 Several studies show slightly decreased levels of tau in PD when compared with controls.2, 3, 5 The rate of change of tau has been shown to be associated with motor progression.26 Thus, there is evidence that tau plays a role in the pathophysiology of PD.