In favor of this theory, we can say that the severity of this type of dementia correlates well with the growing accumulation of neurofibrillary tangles in the brain [11,12,13]; there is a high correlation between hyper-phosphorylated tau species in the cerebrospinal fluid (CSF) in patients with AD and the degree of cognitive impairment [14]; a decrease in tau filaments by drugs directed against this therapeutic target alleviates cognitive deterioration [15]. The gene discussed is MAPT; the disease is Alzheimer disease.