The bomb pulse of 14C (Figure 3) was used to determine the average date of formation of the major histopathological features in AD brain: extracellular senile plaques (SP), composed primarily of Aβ peptide, and intracellular neurofibrillary tangles (NFT), composed of paired helical filaments containing hyperphosphorylated tau proteins [51]. This evidence concerns the gene MAPT and Alzheimer disease.