MAPT and Alzheimer disease: Alzheimer’s disease (AD) is characterized by amyloid-beta (Aβ) deposition, tau pathology, neurodegeneration, and cognitive decline.1 Diagnosing and staging AD has been greatly facilitated by in vivo biomarkers including positron-emission tomography (PET) and cerebrospinal fluid (CSF) markers of Aα and pathologic tau, as well as volumetric magnetic resonance imaging (MRI) and fluorodeoxyglucose (FDG)-PET measures of neurodegeneration.2 Apart from diagnosing AD, a clinically important challenge is predicting the worsening of cognitive impairment.3