MAPT and early-onset autosomal dominant Alzheimer disease: Similarly, the microtubule associated protein tau (MAPT) accumulates not only in neurons affected by Alzheimer’s disease (AD), but in PD and PDD, while mutations that increase the stability of tau result in frontotemporal dementia with parkinsonism (FTDP-17 (or FTD) [Spillantini and Goedert, 2013]).