MAPT and Alzheimer disease: In our sample of 203 cognitively unimpaired individuals (all aged 70 years, 51% female), 2% had an AD biomarker profile (i.e., A+ T+), 43% had abnormal CSF levels of β-amyloid only (i.e., A+ T−), and 4.4% had abnormal CSF levels of p-tau only (i.e., A− T+).