APOE and Alzheimer disease: Research suggests that patients classified as MCI by the actuarial neuropsychological criteria have stronger associations between cognitive function and hippocampal volume [34], higher levels of AD biomarkers (i.e., beta-amyloid, Aβ, total and hyperphosphorylated tau in cerebral spinal fluid, CSF), are more likely to possess the APOE ε4 allele, a genetic risk factor for AD, and more likely to convert to dementia than patients classified as MCI by the conventional criteria [35].