MAPT and Alzheimer disease: In particular, pH in the brain could be significant in the pathophysiology of AD, as low pH has been reported to exacerbate the aggregation of the amyloid-β peptide and hyperphosphorylation of Tau protein, key pathological hallmarks of the disease (Atwood et al., 1998; Basurto-Islas et al., 2013; Decker et al., 2021).