Alzheimer's Disease is characterized pathologically by two principal hallmark lesions: the senile plaque and the neurofibrillary tangle. Since the identification of each over 100 years ago, the major protein components have been elucidated. This has led in turn to the elaboration of metabolic cascades involving amyloid-β production in the case of the senile plaque, and phosphorylated-tau protein in the case of the neurofibrillary tangle. The pathogenesis and histogenesis of each have been the source of extensive investigation and some controversy in recent years, as both cascades have...