APOE and Alzheimer disease: The MCI and AD groups had fewer years of education (MCI 15.9 ± 2.9 vs. NC 16.3 ± 2.7 years, p = 0.03; AD 15.1 ± 3.0 vs NC, p = 0.003), fewer APOE ε2 carriers (MCI 6% vs. NC 14%, p < 0.001; AD 4% vs. NC, p < 0.001), and more APOE ε4 carriers (MCI 49% vs. NC 27%, p < 0.001; AD 68% vs. NC, p < 0.001) than the NC group.