For example, AD brains accumulate neurofibrillary tangles, neurofibrillary tangles contain phosphorylated tau, phosphorylated tau exists in a soluble intermediate form that is toxic to synapses, phosphorylated tau thus is a product of a pathological cascade that is inherently deleterious, and that pathological cascade, if left unchecked, causes neurodegeneration [2]. This evidence concerns the gene MAPT and Alzheimer disease.