July 19, 2023 -- Researchers studying a diet designed to improve brain health say were surprised by the results of a recent experiment because subjects on the MIND diet did not show greater brain health than those on a control diet after three years.
About half of the 604 participants followed the Mediterranean–DASH Intervention for Neurodegenerative Delay diet for three years. The other half had only mild caloric restrictions.
“Among cognitively unimpaired participants with a family history of dementia, changes in cognition and brain MRI outcomes … did not differ significantly between those who followed the MIND diet and those who followed the control diet,” the study’s authors wrote.
The MIND diet did improve the brains of those who followed it for three years. Magnetic resonance imaging scans revealed fewer tiny lesions and more grey matter and white matter, the brain’s cognitive center and “communication highway,” respectively, CNN reported.
But the brains of the participants who were not following the MIND diet showed similar improvement.
“We really expected that the MIND diet would show an effect above the control group, so we were quite surprised by the outcome,” said lead author Lisa Barnes, associate director of the Alzheimer’s Disease Research Center at Rush University Medical Center in Chicago.
The research was published in the New England Journal of Medicine.
The MIND diet includes much of the Mediterranean diet, an eating approach that favors fish, fruits, vegetables, whole grains, beans, and olive oil. The MIND diet also includes part of the Dietary Approaches to Stop Hypertension (DASH) diet, which aims to improve blood pressure and lower risk of heart attacks, strokes and some conditions that can lead to dementia.
CNN reported concerns about the new study.
“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,” said Walter Willett, MD, a professor of epidemiology and nutrition at Harvard T.H. Chan School of Public Health and professor of medicine at Harvard Medical School.
Willett pointed to an older clinical trial which found eating more beta-carotenoids, the antioxidants found in red, yellow, orange and dark green fruits and vegetables, produced cognitive benefits — but only after years on the diet.
Barnes said previous research showed that following the MIND diet and the Mediterranean diet gave significant protection against cognitive decline and Alzheimer’s disease, but that those studies were much longer than the new, three-year study.