Healthy Diets Linked to Lower Cognitive Decline Risk: JAMA

The prospective cohort study was based on the Nurses’ Health Study (1986–2014), the Nurses’ Health Study II (1991–2017), and the Health Professionals Follow-Up Study (1986–2012). The total number of participants was 159,347 adults for whom information on both dietary and cognitive factors. The average age was 44.3 ± 9.3 years. Of the total number of participants, 131,560 (82.6%) were females. The analysis of the data was done between September 2024 and November 2025. The participants had their diets repeatedly measured over time and were given a score for their intake of six different dietary patterns.

The six dietary patterns had scores such as the alternate healthy eating index 2010 (AHEI-2010), DASH diet score, healthful plant-based diet index (hPDI), planetary health diet index (PHDI), and reverse empirical dietary indices for hyperinsulinemia (rEDIH) and inflammatory potential (rEDIP). These indices represent different components of diet quality. The subjective cognitive decline (SCD) was assessed using seven questions that measured perceived change in memory and cognitive abilities. Objective cognition was assessed using telephone-based methods from the Nurses' Health Study.

Key findings:

• Of 159,347 participants, greater adherence to all six healthy dietary patterns was associated with lower risk of SCD.

• The DASH diet had the strongest association. When comparing 90th and 10th percentiles of adherence, the risk ratio for SCD was 0.59 (95% CI: 0.57-0.62), which equates to a 41% lower risk of SCD.

• The second strongest associations were with the healthful plant-based diet index and the reversed empirical dietary index for hyperinsulinemia, with risk ratios of 0.76 (95% CI: 0.65-0.85 and 0.73-0.80, respectively).

• The Planetary Health Diet Index had a risk ratio of 0.80 (95% CI: 0.75-0.86), the AHEI-2010 had a risk ratio of 0.84 (95% CI: 0.80-0.89), and the reversed empirical dietary index for inflammatory pattern had a risk ratio of 0.89 (95% CI: 0.85-0.93).

• Greater adherence to the DASH diet from 45 to 54 years of age had the strongest association with reduced SCD risk.

• For objective cognitive performance, again the DASH diet had the strongest association with SCD, with a mean z-score difference of 0.05 (95% CI, 0.02–0.09) for comparing the 90th vs. 10th percentiles of adherence.

• Vegetables and fish were food groups that were positively associated with cognitive performance, while red and processed meats were negatively associated with cognitive performance.

In this large prospective cohort study, greater adherence to healthy dietary patterns, particularly the DASH diet, was found to be associated with significantly reduced risk of SCD and slightly better objective cognition. The strongest association was found with the DASH diet, with a risk ratio of 0.59 for SCD when comparing the highest and lowest levels of adherence. These data emphasize the importance of a high-quality diet for long-term cognitive health and suggest that dietary interventions in midlife may be an important tool in maintaining cognition with age.

Reference:

Chen H, Cortese M, Flores-Torres MH, et al. Dietary Patterns and Indicators of Cognitive Function. JAMA Neurol. Published online February 23, 2026. doi:10.1001/jamaneurol.2026.0062