This project is led by the Institute for the Advancement of Food and Nutrition Research (IAFNS, www.iafns.org), a nonprofit organization that advances food and nutrition science for public benefit. The principle investigators include Dr. Lyn Steffen, University of Minnesota, US and Dr. Rafael de la Torre Fornell of the IMIM-Hospital del Mar Medical Research Institute, Barcelona, Spain. Background Justification The 2020 Dietary Guidelines Advisory Committee (DGAC) explored neurocognitive health through several systematic reviews and was faced with a literature having “considerable variation in testing methods, inconsistent validity and reliability of cognitive testing methods, and differences between dietary patterns and cognitive outcomes examined,” reducing the ability to draw conclusions (USDA/HHS 2020) . The 2025 DGAC draft questions were released in 2022. The question relevant to this project is: ● “What is the relationship between dietary patterns consumed and risk of cognitive decline, mild cognitive impairment, dementia, and Alzheimer’s disease?” The lack of methodological harmonization is a long-standing challenge in the field, recognized over many decades. As the challenge faced by the 2020 DGAC is likely to still be in place for the 2025 DGAC’s review, one potential solution is to develop an approach to this literature. Therefore, we propose to identify several prospective studies that have examined dietary intake associated with cognitive function, risk of cognitive decline, mild cognitive impairment, dementia, and Alzheimer’s disease, harmonize the data, and conduct a meta-analysis to answer the above study question.