Beyond the brain changes and gradual cognitive decline characteristic of normal aging (Park and Reuter-Lorenz, 2009), the hallmark of Alzheimer's disease is a stereotyped spatial pattern of neuritic plaques (amyloid-β or Aβ) and neurofibrillary tangles (tau), alongside loss of episodic memory and cognitive decline. Here, MAPT is linked to early-onset autosomal dominant Alzheimer disease.