Docosahexaenoic Acid and Adult Memory: A Systematic Review and Meta-Analysis

Introduction: Subjective memory complaints are common with aging. Docosahexaenoic acid (DHA; 22:6 n-3) is a long-chain polyunsaturated fatty acid (LCPUFA) and an integral part of neural membrane phospholipids that impacts brain structure and function. Past research demonstrates a positive association between DHA plasma status/dietary intake and cognitive function. Objectives: The current meta-analysis was designed to determine the effect of DHA intake, alone or combined with eicosapentaenoic acid (EPA; 20:5 n-3), on specific memory domains: episodic, working, and semantic in healthy adults aged 18 years and older. A secondary objective was to systematically review/summarize the related observational epidemiologic literature. Methods: A systematic literature search of clinical trials and observational studies that examined the relationship between n-3 LCPUFA on memory outcomes in healthy adults was conducted in Ovid MEDLINE and EMBASE databases. Studies of subjects free of neurologic disease at baseline, with or without mild memory complaints (MMC), were included. Random effects meta-analyses were conducted to generate weighted group mean differences, standardized weighted group mean differences (Hedge’s g), z-scores, and p-values for heterogeneity comparing DHA/EPA to a placebo. A priori sub-group analyses were conducted to evaluate the effect of age at enrollment, dose level, and memory type tested. Results: Episodic memory outcomes of adults with MMC were significantly (P 1 g/day DHA/EPA improved episodic memory (P