Several Healthy Diets Found to Lower the Risk for Cognitive Decline in New Study

Multiple healthy diets, especially the Dietary Approaches to Stop Hypertension-style diet, were tied to better cognitive function and a lower risk for cognitive decline, according to a new study published in JAMA Neurology.¹

Prior studies have suggested that some healthy diets may have protective effects against cognitive impairment while raising the odds of healthy aging.²

But the role of diet in cognitive health “is still uncertain,” Hui Chen, PhD, from the department of nutrition at Harvard T.H. Chan School of Public Health, and colleagues wrote.

“Discrepancies in existing studies may arise from differences in study design, study populations, follow-up durations, and exposure and outcome measurements,” they wrote. “Additionally, short follow-up periods and the lack of repeated dietary assessments to capture long-term intake limit causal inference, as the extended preclinical phase of dementia may lead to behavioral changes and memory impairments that confound dietary reporting.”

In the current study, Chen and colleagues utilized 1986 to 2017 data taken from the Nurses’ Health Study, Nurses’ Health Study II and Health Professionals Follow-Up Study to assess the impact of six dietary patterns on subjective cognitive decline (SCD) and objective cognitive function.

The diets included the Dietary Approaches to Stop Hypertension (DASH)-style diet, the Healthful Plant-Based Diet Index (hPDI), the Alternate Healthy Eating Index 2010 (AHEI-2010), the Planetary Health Diet Index (PHDI) and the reversed empirical dietary indices for hyperinsulinemia (rEDIH) and inflammatory pattern (rEDIP).

Chen and colleagues assessed SCD through several questions on perceived changes in cognitive processes like memory and attention, while cognitive function was measured through telephone-based assessments in the Nurses’ Health Study.

The cohort included 159,347 people (mean age, 44 years; 82.6% women).

The researchers reported that higher adherence to all six diets decreased the risk for SCD. The DASH-style diet had the greatest effect, lowering the risk by 41% (RR = 0.59; 95% CI, 0.57-0.62), followed by the:

• hPDI (RR = 0.76; 95% CI, 0.65-0.85);
• rEDIH (RR = 0.76; 95% CI, 0.73-0.8);
• PHDI (RR = 0.8; 95% CI, 0.75-0.86);
• AHEI-2010 (RR = 0.84; 95% CI, 0.8-0.89); and
• rEDIP (RR = 0.89; 95% CI, 0.85-0.93).

Certain food groups, including greenleafy, yellow and other vegetables, fruits, fish, wine, salad dressing and tea were tied to better cognitive outcomes, while fried potatoes, red and processed meats, sugary drinks, eggs, nuts and seeds were linked to worse cognitive outcomes.

Regarding mechanisms behind the DASH-style diet’s associations, “although direct evidence for the mediation role of hypertension in diet-cognition pathways remains limited, our findings aligned with prior literature on the cognitive benefits of BP control and cognitive health,” the researchers wrote.

They noted that the associations of some of the other diets like rEDIH and rEDIP “might be diluted by components that are less cognition specific” but that the results “generally supported the role of insulin and inflammatory pathways in cognitive health.”

Chen and colleagues acknowledged there were some study limitations. For example, SCD in the study was self-reported “and may be influenced by differences in health awareness or reporting tendencies.”

“Better adherence to a healthy diet, exemplified by the DASH diet, from midadulthood, exhibited stronger associations. These findings support the importance of healthy eating as part of midlife brain-health strategies and motivate pragmatic and implementation research to translate these findings into scalable programs,” researchers concluded.

References:

1. 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
2. Yuan C, Cao Y, Ascherio A, et al. Long-term diet quality and its change in relation to late-life subjective cognitive decline. Am J Clin Nutr. 2022;115(1):232-243. doi:10.1093/ajcn/nqab326