MAPT and Alzheimer disease: We and others have previously shown that phosphorylated-tau oligomers are enriched in the synapses of human AD brain tissue, as compared to control, while total tau remains the same between the synaptic and cytosolic fractions (Henkins et al., 2012; Tai et al., 2012, 2014; Perez-Nievas et al., 2013; Sokolow et al., 2015; Zhou et al., 2017).