The cerebrospinal fluid (CSF) biomarkers of these processes—amyloid-β 1–42 (Aβ42), total tau, and tau phosphorylated at threonine 181 (p-tau)—show very consistent changes in AD dementia and prodromal AD [2], and they have been included as evidence for the presence of AD pathology in research diagnostic criteria for AD [3, 4]. This evidence concerns the gene MAPT and Alzheimer disease.