Dietary patterns in middle age: Effects on concurrent neurocognition and risk of age-related cognitive decline

Context: Diet plays a critical role in cognitive integrity and decline in older adults. However, little is known about the relationship between diet and cognitive integrity in middle age. Objective: To investigate the relationship between dietary patterns in healthy middle-aged adults and neurocognition both in middle age and later in life. Data Sources: Using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, the following electronic databases were searched: Web of Science, Scopus, PubMed, and PsychInfo. Data Extraction: Data from eligible articles was extracted by 2 reviewers. Data Analysis: Articles included in the systematic review were synthesized (based on the synthesis without meta-analysis reporting guidelines) and assessed for quality (using the Joanna Briggs Institute checklist for randomized controlled trials, cohort studies, and cross-sectional studies) by 2 reviewers. Results: Of 1558 studies identified, 34 met the eligibility criteria for inclusion. These comprised 9 cross-sectional studies, 23 longitudinal or prospective cohort studies, and 2 randomized controlled trials. Findings were mixed, with some studies reporting a significant positive relationship between adherence to various "healthy"dietary patterns and neurocognition, but others reporting no such relationship. Conclusion: This systematic review demonstrated that adherence to the Mediterranean diet and other healthy dietary patterns in middle age can protect neurocognition later in life. Systematic Review Registration: PROSPERO registration no. CRD42020153179.