MAPT and Alzheimer disease: Indeed, in recent years there has been tremendous progress in the development of AD diagnostic imaging biomarkers, including FDA-approved brain amyloid imaging via positron emission tomography (PET), as well as tau, surrogate markers of inflammation such as TSPO, and synaptic PET imaging (Rabinovici et al., 2007; Schilling et al., 2016; Chen et al., 2018; Edison et al., 2018; Narayanaswami et al., 2018; Chandra et al., 2019; Werry et al., 2019).