For example, since the 1990s, validation of in vivo AD pathology has relied on imaging biomarkers, initially with non–AD‐specific magnetic resonance imaging (MRI) scans31, 32, 33 that later gave way to AD‐specific positron emission tomography (PET) scans34 that used tracers of amyloid and tau, both of which have recently received FDA approval because of their high levels of biomarker specificity.35 This evidence concerns the gene MAPT and Alzheimer disease.