The present clinical and neuropathological diagnostic guidelines are derived from the assumptions that (1) depositions of the amyloids and tangles are more severe in the Alzheimer brain, compared to the brain of subjects with normal cognitive aging, and so, (2) Aβ and Tau depositions should be a specific marker of both preclinical and symptomatic stages of Alzheimer’s disease. This evidence concerns the gene MAPT and early-onset autosomal dominant Alzheimer disease.