MAPT and Alzheimer disease: Well-established core biomarkers that reflect AD pathology and show promising performance in evaluating AD risk and diagnosing AD are the 42 amino acid form Aβ (Aβ42), the ratio of Aβ42/40, phosphorylated tau (P-tau), and total tau (T-tau) in the cerebrospinal fluid (CSF) (Blennow et al., 2012).