Dietary patterns in early life pay dividends for midlife cognitive performance

The pathologic features of Alzheimer dementia may be seeded many years before the clinical diagnosis, which suggests that risk factor modification early in life may be the best strategy for the prevention of late-onset Alzheimer disease.¹ There is literature suggesting that diet and nutritional factors can promote cognitive health in late life²; however, in this issue of Neurology®, McEvoy et al.³ report that adherence to specific dietary patterns in early adulthood is associated with cognitive health in midlife. The authors examined diet using a validated questionnaire administered over 3 time points to assess adherence to a Mediterranean-style diet (MedDiet), the Dietary Approaches to Stop Hypertension (DASH), and the A Priori Diet Quality Score (APDQS). The study population was the large and racially diverse Coronary Artery Risk Development in Young Adults (CARDIA) study of 2,621 men and women with a mean age of 25 to 45 years at the first dietary assessment. Associations with cognitive performance at the ages of 50 and 55 years and the change in cognitive function between the ages of 50 and 55 years were examined. The results indicate that the MedDiet and APDQS diet offer benefit to cognitive health, while associations for the DASH diet were mostly insignificant. The components of each of these dietary patterns that appeared to yield the most benefit included the higher intake of monounsaturated fats over saturated fat and the higher intake of legumes that are good sources of phytonutrients, protein, fiber, and micronutrients (folate, thiamin, iron, magnesium, potassium, and zinc) (supplemental material). The authors reasonably controlled for potential confounders of the association between dietary patterns and cognitive function and confirmed the internal consistency of the results through a series of sensitivity analyses. A notable strength of the study is the repeated within-person administration of the dietary questionnaires over 3 time points, which can permit the averaging of the dietary intake reports across each participant and can improve the accuracy of the subjective reporting of dietary intake.⁴ Limitations of the study, other than its observational nature, which raises questions about causality, are the relatively short duration of follow-up between cognitive assessments (≈5 years) and the absence of objective biochemical measures of diet (i.e., nutrient biomarkers) to substantiate the findings and to uncover potential mechanisms of action.