MAPT and Alzheimer disease: Abnormal levels of amyloid-β 1-42 (Aβ42), total tau (t-tau) and tau phosphorylated at threonine 181 (p-tau-181) are biomarkers for the presence of Alzheimer’s disease (AD) pathology in the brain [1], and part of established research criteria for AD across the cognitive continuum [2, 3].