Perspective: Advancing Dietary Guidance for Cognitive Health-Focus On Solutions to Harmonize Test Selection, Implementation, and Evaluation.

This perspective article is a product of a workshop of experts convened by the Institute for the Advancement of Food and Nutrition Sciences (IAFNS), a nonprofit organization that brings together scientists from government, academia, and industry to catalyze science relevant to food and nutrition. An expert group was convened in March 2022 to discuss the current issues surrounding cognitive task selection in nutrition research, with a focus on solutions toward informing dietary guidance for cognitive health, to address a gap identified in the 2020 United States Dietary Guidelines Advisory Committee report, specifically the "considerable variation in testing methods used, [and] inconsistent validity and reliability of cognitive testing methods." To address this issue, we first undertook an umbrella review of relevant reviews already undertaken; these indicate agreement on some of the issues that affect heterogeneity in task selection, and on many of the fundamental principles underlying the selection of cognitive outcome measures. However, resolving the points of disagreement is critical to ensuring a meaningful impact on the issue of heterogeneity in task selection; these issues hamper the evaluation of existing data for informing dietary guidance. This summary of the literature is therefore followed by the expert group's perspective in the form of a discussion of potential solutions to these challenges, with the aim of building on the work of previous reviews in the area and advancing dietary guidance for cognitive health. Registered on PROSPERO: CRD42022348106. Data described in the manuscript, code book, and analytic code will be made publicly and freely available without restriction at doi.org/10.17605/OSF.IO/XRZCK.