Omega-3 fatty acids and cognitive decline: modulation by ApoEε4 allele and depression

Long-chain omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may slow cognitive decline. The ε4 allele of the ApolipoproteinE (ApoE), the main genetic risk factor for Alzheimer's disease, and depressive symptoms, which are frequently associated with cognitive impairment in older persons, may modify this relationship. We estimated the associations between EPA and DHA plasma levels and subsequent cognitive decline over 7 years, taking into account ApoE-ε4 status and depressive symptoms, in a prospective population-based cohort. Participants (≥ 65 years, n = 1,228 nondemented at baseline) were evaluated at least once over three follow-up visits using four cognitive tests. Plasma EPA was associated with slower decline on Benton Visual Retention Test (BVRT) performances in ApoE-ε4 carriers, or in subjects with high depressive symptoms at baseline. Plasma DHA was associated with slower decline on BVRT performances in ApoE-ε4 carriers only. EPA and DHA may contribute to delaying decline in visual working memory in ApoE-ε4 carriers. In older depressed subjects, EPA, but not DHA, may slow cognitive decline.