Accumulating evidence indicates that Alzheimer’s disease is a continuum in that cognitive impairment in Alzheimer’s disease occurs continuously over a long period and the aggregation of Aβ deposits and tau protein in the brain is also a continuous process beginning before symptom onset [3,9,10,11,12,13,14,15,16]. The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.