MAPT and Alzheimer disease: Whereas, the etiology of AD is not completely understood due to its being complex and multifactorial, low level of acetylcholine (ACh), β-amyloid (Aβ) aggregation, tau-protein hyperphosphorylation, oxidative stress, etc. (Grundke-Iqbal et al., 1986; Talesa, 2001; Hardy, 2009; Rosini et al., 2014) all have been correlated at some extent to AD.