MAPT and early-onset autosomal dominant Alzheimer disease: The amyloid and tau hypotheses of Alzheimer disease pathogenesis suggest that amyloid and tau‐related neurodegeneration occur as separate but sequential pathologic events where amyloid beta drives the pathogenesis of Alzheimer disease and tau neuropathology occurs secondarily and closer to the onset of progressive cognitive decline (Kametani & Hasegawa, 2018; Leuzy et al., 2019).