APOE ε4 carriage was a significant risk factor for all-cause dementia in MAP [HR (95%CI): 1.99 (1.49, 2.66)] and WHIMS [HR (95%CI): 2.08 (1.89, 2.30)] but not in CHAP-White [HR (95%CI): 1.80 (0.76, 4.29)] or CHAP-Black [HR (95%CI): 1.20 (0.46, 3.15)] cohorts. Here, APOE is linked to dementia.