MAPT and Alzheimer disease: The other combinations of CSF biomarkers have also been evaluated, which suggested that the high CSF p-tau/Aβ42 ratio possesses higher sensitivity and specificity [18] for differentiating AD from normal controls and from subjects with other non-AD dementia than that of the CSF t-tau, p-tau, Aβ42, and ratio of t-tau/Aβ42.