MAPT and dementia: In contrast, among Aβ-positive participants with MCI and dementia, from age 60 years to 80 years, the estimated prevalence of tau positivity decreased from 68.0% (95% CI 60.4–75.6%) to 52.9% (95% CI 46.3–59.5%) in MCI and from 91.5% (95% CI 88.8–94.3%) to 74.6% (95% CI 69.4–79.7%) in dementia (Fig. 1b,c, Table 2 and Supplementary Table 2).