The past 30 years of Alzheimer's disease research have led to the certain proof that accumulation of abnormally folded amyloid β (Aβ) and tau proteins (hyper-phosphorylated tau; p-tau) in amyloid plaques and neuronal tangles, respectively, are causally connected to the typical neurodegenerative process in patients' brains (Karran et al., 2011; De Strooper and Karran, 2016; Scheltens et al., 2016). This evidence concerns the gene MAPT and early-onset autosomal dominant Alzheimer disease.