Among Aβ-negative participants with MCI and dementia, from age 60 years to 80 years, the estimated prevalence of tau positivity increased from 4.1% (95% CI 1.9–6.2%) to 11.0% (95% CI 6.0–16.0%) in MCI and from 9.7% (95% CI 6.1–13.2%) to 14.4% (95% CI 6.3–22.5%) in dementia (Fig. 1b,c and Table 2). This evidence concerns the gene MAPT and dementia.