MAPT and Parkinson disease: Since α-syn pathology does not appear to be necessary for nigrostriatal degeneration in subjects with MMD, we examined the potential for tau to mediate this process, since tau has been shown previously to be a co-pathology in PD,14,30 and knockout of tau in preclinical models attenuates and delays neurodegeneration associated with α-syn.31 We examined tau pathology in all participants in this study.