MAPT and Alzheimer disease: Homologousbinding assays in human post-mortem brain tissue (Table 3) demonstrated that [3H]75 binds with high affinity (KD = 1–1.5 nM) in AD (mixed 3R/4R-tau), PSP (4R-tau),and CBD (4R-tau), and with slightly reduced affinity (KD ∼ 3.8 nM) in PiD (3R-tau).