MAPT and Alzheimer disease: Old age is a major AD risk factor: the annual AD incidence increases from 1% between ages of 60 and 70 years to 6–8% at the age of 85 or older.1, 2 AD is characterized by misfolded protein pathological brain hallmarks: extracellular deposits of amyloid-β (Aβ) plaques and accumulation of phosphorylated tau neurofibrillary tangles.