MAPT and early-onset autosomal dominant Alzheimer disease: To better understand the evolution of Alzheimer’s disease in its earliest stages, CSF characteristics were explored in a subset of CN middle-aged individuals (50–75 years) in the Emory Healthy Brain Study (EHBS22), including a subset of 134 individuals with CSF levels of Aβ42, total Tau (tTau) and phospho181-Tau (pTau) indicative of underlying Alzheimer’s disease pathology.