MAPT and Alzheimer disease: Specifically, measurement of tau and Aβ in CSF, or quantitation of amyloid or tangle pathology by PET imaging, can be used to identify mild cognitive impairment (MCI), a frequent precursor of AD (Jack et al., 2013; Bao et al., 2017), and use of these markers is now common in clinical research (Blennow et al., 2012; Jack et al., 2013).