Mediterranean and DASH diets linked to slower cognitive decline in older adults

An analysis of data from the Health and Retirement Study found that individuals adhering to the Mediterranean diet and the Dietary Approaches to Stop Hypertension (DASH) diet experience slower cognitive decline. A dietary pattern combining these two diets, designed to promote brain health, was associated with better cognitive functioning at the start of the study but not with slower cognitive decline. The paper was published in the Journal of the Academy of Nutrition and Dietetics.

Diet plays a critical role in overall health, including mental health. While scientists have long known that insufficient intake of certain nutrients or their complete absence can cause serious diseases and adverse health conditions, recent studies have also started exploring the effects of complex dietary patterns on health. These studies have identified that certain dietary patterns—such as those based on foods high in easily digestible sugar and fats or on ultra-processed foods—can produce adverse health consequences (e.g., obesity) or increase the risk of various diseases.

Conversely, researchers have identified dietary patterns associated with reduced disease risk or other health benefits. For example, dietary patterns rich in lean proteins, fruits, and vegetables and low in ultra-processed foods have been described as neuroprotective and potentially able to slow cognitive decline in old age. Similarly, beneficial effects have been ascribed to the Mediterranean diet. The Mediterranean diet, inspired by traditional diets of countries bordering the Mediterranean Sea, emphasizes the intake of fruits, vegetables, whole grains, nuts, olive oil, fish, and moderate wine consumption while limiting red meat and processed foods.

Study author Elayna R. Seago and her colleagues sought to examine the association between the Mediterranean diet, the Dietary Approaches to Stop Hypertension (DASH) diet, and the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet and global cognition over six years.

The DASH diet is designed to lower blood pressure and emphasizes fruits, vegetables, whole grains, lean proteins, and low-fat dairy while reducing sodium, saturated fats, and added sugars. The MIND diet, a hybrid of the DASH and Mediterranean diets, is tailored to support brain health and reduce the risk of Alzheimer’s disease by focusing on specific foods such as leafy greens, berries, nuts, and olive oil.

The researchers analyzed data from the Health and Retirement Study, a nationally representative longitudinal study of older adults in the United States. This study, sponsored by the National Institute on Aging and conducted by the University of Michigan, collected data between 2014 and 2020, including information on participants’ food intake.

The analysis excluded individuals with very high or very low caloric intake, participants with diagnoses of dementia, Alzheimer’s disease, or stroke in 2014, and individuals younger than 50 years of age when they completed their dietary assessment in 2013–2014. In total, data from 6,154 participants were analyzed.

The researchers used participants’ responses to the Harvard Food Frequency Questionnaire to calculate scores indicating adherence to the three dietary patterns: the Mediterranean diet, the DASH diet, and the MIND diet. They also created a composite measure of cognitive functioning based on various cognitive tests completed by study participants.

The results showed that adherence to each of the three dietary patterns was associated with better cognitive functioning at the start of the study. Additionally, adherence to the Mediterranean and DASH diets was associated with slower cognitive decline over the six-year study period, while adherence to the MIND diet was not associated with the pace of cognitive decline.

“There is accumulating evidence that certain neuroprotective diets are associated with more intact cognitive function in older adults. This study provides complementary evidence with these findings by showing that the Mediterranean, DASH, and MIND diets are associated with better cognition at baseline, and also demonstrates that the Mediterranean and DASH diet patterns were also associated with reduced rate of cognitive decline over 6 subsequent years,” the study authors concluded.

The study sheds light on the links between diet and cognitive functioning in old age. However, it should be noted that data on dietary patterns were self-reported, leaving room for reporting bias. Additionally, the study’s design does not allow for causal inferences to be drawn from the results.

The paper, “Neuroprotective Dietary Patterns and Longitudinal Changes in Cognitive Function in Older Adults,” was authored by Elayna R. Seago, Brenda M. Davy, Kevin P. Davy, and Ben Katz.