Among ε4/ε4 individuals, AD risk increased substantially in a dose-dependent manner with the number of <i>APOE</i> promoter SNP rs405509 <i>T</i> alleles in EastAs <i>(TT</i>: OR (odds ratio) = 27.02, <i>p</i> = 8.80 × 10<sup>-94</sup>; <i>GT</i>: OR = 15.87, <i>p</i> = 2.62 × 10<sup>-9</sup>) and EuroAs (<i>TT</i>: OR = 18.13, <i>p</i> = 2.69 × 10<sup>-108</sup>; <i>GT</i>: OR = 12.63, <i>p</i> = 3.44 × 10<sup>-64</sup>), and rs405509-<i>T</i> homozygotes had a younger onset and more severe cortical atrophy than those with <i>G</i>-allele.