Alzheimer disease (AD) is a progressive cognitive disorder leading to dementia1 in which the brain gradually accumulates both amyloid-β (Aβ) and tau pathologies.2 Autopsy studies identified the early stages of Aβ and tau pathologies in individuals who were clinically normal during life, representing a preclinical stage of AD.3 Based on autopsy studies,4 the prevailing research hypothesis posits that Aβ precedes and accelerates neocortical tau pathology, which together precipitate cognitive decline. The gene discussed is MAPT; the disease is cognitive disorder.