APOE and Alzheimer disease: Compared with noncarriers, these MCI patients are more likely to have underlying AD pathology; that is, they are more likely to classify as prodromal AD according to the Albert criteria, since APOE ε4 positivity in MCI has been found to be associated with amyloid positron emission tomography positivity, and with the AD biomarker profile in cerebrospinal fluid [31-33].