A new study published Feb. 23 in JAMA Neurology reports that what people eat in middle age can significantly affect how well their brains function later in life. Researchers found that healthier eating patterns during midlife are associated with a lower risk of cognitive decline in older adulthood.

The study, led by Dr. Kjetil Bjornevik, an assistant professor of epidemiology and nutrition at Harvard T.H. Chan School of Public Health, analyzed data from more than 159,000 participants drawn from three long-running health studies of nurses and other medical professionals. Researchers evaluated how closely participants adhered to six recognized healthy dietary patterns and then compared those scores to self-reported cognitive function in later life.

Among the diets studied, the Dietary Approaches to Stop Hypertension (DASH) diet showed the strongest protective association. Participants whose eating habits most closely aligned with DASH had a 41% lower risk of brain decline compared to those with the lowest adherence. The strongest association was observed among individuals between the ages of 45 and 54.

The DASH diet emphasizes vegetables, fruits, whole grains, fish, and moderate wine consumption, while limiting red and processed meats, fried foods, and sugary beverages. According to the researchers, higher intake of vegetables and fish and moderate wine consumption were linked to better cognitive outcomes, whereas red and processed meats, fried potatoes, and sugary drinks were associated with poorer cognition.

Other dietary patterns, including the Healthful Plant-Based Diet Index, the Planetary Health Diet Index, and the Alternate Healthy Eating Index 2010, were also associated with reduced risk of brain decline, though the effect was smaller, ranging from 11% to 24%.

Stephanie Schiff, a registered dietitian and nutritionist at Northwell Health in Huntington, New York, who was not involved in the study, said the findings challenge the assumption that cognitive decline is inevitable with age. She noted that maintaining cardiovascular health plays a key role in preserving brain function.

High blood pressure can damage blood vessels throughout the body, including those supplying the brain. Reduced blood flow may limit oxygen delivery, potentially contributing to memory loss, reduced executive function, and increased Alzheimer’s risk.

Researchers concluded that adopting a healthy diet in midlife may provide long-term benefits for cognitive health, reinforcing the link between heart health and brain health.