MAPT and Alzheimer disease: The recent research framework for AD proposes an A/T/N classification system based on biomarkers in living patients, independently of cognitive status: “A” refers to the Aβ biomarker (Aβ PET or CSF), “T” refers to pathologic Tau (CSF pTau or PET-Tau), and “N” refers to neurodegeneration (CSF tTau, FDG-PET, or structural MRI) [42].