MAPT and Alzheimer disease: For a treatment effect of 25%, the sample size was reduced by 50.2% (±7.1) for participants at risk of the onset of AD, by 40.9% (±4.9) for a trial targeting individuals with preclinical AD and high brain amyloid levels, by between 38.1% (±1.6) and 45.4% (±2.0), depending on the outcome considered, for subjects with early AD and high levels of brain amyloid, by 44.6% (±3.9) for subjects with early AD and high brain levels of tau, and by 43.1% (±0.8) for participants with mild cognitive impairment probably due to AD or mild AD.