MAPT and Alzheimer disease: Prior research has identified various blood markers for AD, with investigations focusing on amyloid-beta (Aβ) (Olsson et al., 2016; Nakamura et al., 2018), tau proteins (Olsson et al., 2016; Mielke et al., 2018), and neurofilament light—a structural protein indicating neurodegeneration (Mattsson et al., 2017; Khalil et al., 2018).