APOE and Alzheimer disease: In stratified analyses, a trend towards a lower risk of AD was observed per SD increase in RBC DHA for the linear trend in APOE-ε4 carriers (HR: 0.71, 95% CI: 0.51, 1.00, p = 0.053), but not in non-carriers (HR: 0.85, 95% CI: 0.65, 1.11, p = 0.240).