MAPT and Alzheimer disease: The core cerebrospinal fluid (CSF) biomarkers Aβ42, total-tau (t-tau), and phosphorylated tau at threonine 181 (p-tau 181) have demonstrated high diagnostic validity in differentiating AD from healthy controls and other neurodegenerative dementias but with little added value in the assessment of prognosis or disease severity staging (Hampel et al., 2008; Llorens et al., 2016; Abu-Rumeileh et al., 2018).