MAPT and Alzheimer disease: We next examined retinal AT8+ p-tau signals (Fig. 4a, lower panel and Fig. 4e) in a subset of donors with MCI (n = 8, mean age 89.75 ± 5.50 years, 4 females/4 males), AD (n = 21, mean age 82.81 ± 13.40 years, 10 females/11 males), and NC controls (n = 18, mean age 81.50 ± 8.96 years, 9 females/9 males).