At present, the definitive diagnosis of AD still depends on an autopsy of the brain, by the histopathological identification of amyloid precursor protein’s (APP) hallmark proteolytic products, β-amyloid (Aβ) peptides, and intracellular neurofibrillary tangles (Sisodia and Price, 1995; Hardy and Selkoe, 2002). Here, APP is linked to Alzheimer disease.