MAPT and Alzheimer disease: In CSF, brain pathology of AD is reflected by lower levels of amyloid-β 1-42 (Aβ42), lower ratio of Aβ42 and amyloid-β 1-40 (Aβ40), and higher levels of hyperphosphorylated tau (P-tau), whereas greater intensity of neurodegeneration correlate with higher CSF levels of total tau (T-tau).32