MAPT and Alzheimer disease: The levels of beta-amyloid peptide (Aβ), total tau (t-tau), and phospho-tau (p-tau) in CSF are used as specific biomarkers of AD, since they reflect the pathologic processes of Aβ42 aggregation and tau’s hyperphosphorylation, respectively, and are included within the support criteria for the clinical diagnosis of probable AD [8].