Nutrition and brain aging: role of fatty acids with an epidemiological perspective

In the absence of identified etiologic treatment for dementia, the potential preventive role of nutrition may offer an interesting perspective. The objective of the thesis of C. Samieri was to study the association between nutrition and brain aging in 1,796 subjects, aged 65 y or older, from the Bordeaux sample of the Three-City study, with a particular emphasis on fatty acids. Considering the multidimensional nature of nutritional data, several complementary strategies were used. At the global diet level, dietary patterns actually observed in the population were identified by exploratory methods. Older subjects with a ‘‘healthy’’ pattern, who consumed more than 3.5 weekly servings of fish in men and more than 6 daily servings of fruits and vegetables in women, showed a better cognitive and psychological health. Adherence to the Mediterranean diet, measured according to a score-based confirmatory method, was associated with slower global cognitive decline after 5 y of follow-up. At the nutrient biomarker level, higher plasma eicosapentaenoic acid (EPA), a long-chain omega-3 fatty acid, was associated with a decreased dementia risk, and the omega-6-to-omega-3 fatty acids ratio to an increased risk, particularly in depressed subjects. EPA was also related to slower working memory decline in depressed subjects or in carriers of the e4 allele of the ApoE gene. Docosahexaenoic acid was related to slower working memory decline only in ApoE4 carriers. Overall, this work suggests a positive impact of a healthy diet rich in fruits and vegetables and fish, and notably the Mediterranean diet, on cognition in older subjects. Long-chain n-3 PUFA, in particular EPA, may be key protective nutrients against risk of dementia and cognitive decline