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

• Published in: PloS one Vol. 10; no. 3; p. e0120391
• Main Authors: Yurko-Mauro, Karin, Alexander, Dominik D., Van Elswyk, Mary E.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 18.03.2015; Public Library of Science (PLoS)
• Subjects: Adult; Adults; Age; Age factors; Aging; Analysis; Blood levels; Brain; Brain research; Clinical trials; Clinical Trials as Topic; Cognitive ability; Dementia; Diet; Dietary intake; Dietary supplements; Docosahexaenoic acid; Docosahexaenoic Acids - pharmacology; Drug Interactions; Eicosapentaenoic acid; Eicosapentaenoic Acid - pharmacology; Epidemiology; Fatty acids; Functional anatomy; Gene expression; Heterogeneity; Humans; Lipids; Medical research; Memory; Memory - drug effects; Meta-analysis; Nervous system diseases; Observational studies; Observational Studies as Topic; Older people; Omega 3 fatty acids; Phospholipids; Polyunsaturated fatty acids; Short term memory; Structure-function relationships; Studies; Systematic review; Unsaturated fatty acids; United States > US; Colorado
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0120391

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. 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. 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. Episodic memory outcomes of adults with MMC were significantly (P<.004) improved with DHA/EPA supplementation. Regardless of cognitive status at baseline, > 1 g/day DHA/EPA improved episodic memory (P<.04). Semantic and working memory changes from baseline were significant with DHA but no between group differences were detected. Observational studies support a beneficial association between intake/blood levels of DHA/EPA and memory function in older adults. DHA, alone or combined with EPA, contributes to improved memory function in older adults with mild memory complaints.