Blood biomarkers serve as quantitative measures of brain injury and could potentially predict cognitive impairment.3, 4 Biomarkers phosphorylated tau at threonine 181 (p-tau181), total tau (t-tau), amyloid-beta peptides 40 (Aβ40) and 42 (Aβ42) demonstrate Alzheimer disease related changes and often correlate with cognitive decline, these are hereafter summarized as “Alzheimer disease biomarkers”.5 This evidence concerns the gene MAPT and early-onset autosomal dominant Alzheimer disease.