Compared to those with neither IHD nor APOE ε4, there was an elevated progression rate to MCI/AD dementia in subjects with either IHD (HR = 1.591, 95 % CI =1.064 –2.379, p = 0.024) or APOE ε4 (HR = 2.724, 95 % CI = 2.213–3.352, p < 0.001) alone; individuals with both IHD and APOE ε4 had tripled risk of MCI/AD (HR = 3.17, 95 % CI = 2.207–4.554, p < 0.001). This evidence concerns the gene APOE and Alzheimer disease.