Alzheimer's disease (AD) brains are characterized by extracellular aggregates of the small (40 and 42 residues) β-amyloid peptide (Aβ) [1], and intraneuronal neurofibrillary tangles, composed of hyperphosphorylated tau assembled in paired helical filaments [2]. This evidence concerns the gene MAPT and early-onset autosomal dominant Alzheimer disease.