APOE genotype acts in conjunction with other genetic and/or environmental factors to confer AD risk: the lifetime risk of dementia or mild cognitive impairment is 31%–40% for ε4/ε4 homozygotes [8] but the effects of APOE ε4 have been shown to be modified by ethnic background and sex [5, 9]. Here, APOE is linked to Cognitive impairment.