Joint association between the number of APOE ε4 alleles and educational attainment in relation to dementia risk. Results were adjusted for age, sex, Townsend deprivation index, moderating drinking, current smoking, healthy diet score, obesity, diabetes, hypertension, depression, social isolation, hearing problem, regular physical activity, high cholesterol, cardiovascular disease and traumatic brain injury, the first 10 genetic principal components, relatedness, and genotyping array