A recent clinical trial on the Mediterranean-DASH Diet Intervention for Neurodegenerative Delay (MIND) diet, specifically designed to enhance brain function, has yielded results that were less conclusive than initially anticipated. The study, presented at the 2023 Alzheimer's International Conference in Amsterdam, revealed that while participants following the MIND diet showed improvements in brain health, a control group also experienced similar benefits.
Unexpected Outcomes
Lisa Barnes, associate director of the Alzheimer’s Disease Research Center at Rush University Medical Center in Chicago and lead author of the study, expressed surprise at the findings. “We really expected that the MIND diet would show an effect above the control group, so we were quite surprised by the outcome,” she stated. Magnetic resonance imaging (MRI) scans indicated that individuals adhering to the MIND diet for three years exhibited fewer white matter hyperintensities (tiny lesions) and a larger volume of both grey and white matter. However, these improvements were mirrored in the control group, which did not follow the MIND diet.
Study Details and Design
The study, published in the New England Journal of Medicine, involved 604 overweight individuals over the age of 65, all with a first-degree relative with Alzheimer’s disease and normal cognitive function at the beginning of the trial. The experimental group was instructed to follow the MIND diet while reducing their daily caloric intake by 250 calories, with guidance from a counselor. They also received monthly supplies of olive oil, blueberries, and nuts. The control group was advised to maintain their regular diet, also aiming to reduce caloric intake by 250 calories with counseling support, and received monthly gift cards.
Expert Perspectives
Walter Willett, a professor of epidemiology and nutrition at Harvard T.H. Chan School of Public Health and professor of medicine at Harvard Medical School, suggested that the relatively short duration of the trial might have influenced the results. “My main concern with this trial from the beginning has been that three years may be too short a time to have an impact on a disease process that develops over many decades,” Willett noted. He referenced a previous trial where cognitive benefits from beta-carotene supplementation were only observed after 15 or more years.
Impact of Dietary Changes in Control Group
Barnes also pointed out that participants in the control group may have altered their diets, leading to improvements in their cognitive function. “It’s not like people who were on the control diet stayed flat,” she said. “Everyone was eating healthier, losing weight, and so they all got better. My takeaway is that regardless of the type, a healthy diet does seem to improve cognitive function.” Both groups experienced an average weight loss of five kilograms (11 pounds) during the study.
The MIND Diet: Components and Benefits
The MIND diet, developed in 2015 by researchers at Rush University in Chicago, combines elements of the Mediterranean and DASH diets, emphasizing foods known to promote brain health. Key components include daily consumption of dark leafy greens, berries at least five times a week, three servings of whole grains daily, beans in four meals per week, poultry twice a week, and fish at least once a week. The diet also recommends limiting butter, cheese, red meat, fried foods, pastries, and sweets.
Implications and Future Research
Despite the trial's findings, experts emphasize that the extensive research supporting the benefits of the Mediterranean and DASH diets remains valid. David Katz, a specialist in preventive and lifestyle medicine, noted that various high-quality diets, not just the MIND diet, could offer comparable cognitive benefits. The trial highlights the complexities of nutritional studies and the challenges in isolating the effects of specific dietary interventions over relatively short periods.
