Our findings that these Alzheimer’s disease pathology-dependent increases were already detectable in the 10-year time frame prior to CSF/PET-confirmed amyloid-β pathology in cognitively still unimpaired individuals suggest that Alzheimer’s disease-related changes in plasma p-tau levels are already present in very early stages of Alzheimer’s disease development. This evidence concerns the gene MAPT and early-onset autosomal dominant Alzheimer disease.