MAPT and Alzheimer disease: The diagnosis and monitoring of and the evaluation of treatment efficacy for AD rely significantly on biomarkers, which can be classified into three types [4]: (a) neurodegenerative markers, including those detected by structural/functional imaging and levels of tau and neurofilament light in the cerebrospinal fluid (CSF); (b) biomarkers of tau, such as the detection of p-tau181 in CSF and p-tau217 in plasma or through PET imaging of tau; (c) and biomarkers of βA, such as those detected via PET imaging of amyloid and βA42 levels and the βA42/βA40 ratio in the CSF [5,6].