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Adhering in midlife to the MIND diet -- a hybrid of the Mediterranean diet and the DASH (Dietary Approaches to Stop Hypertension) diets -- was linked with higher volumes in certain brain regions, data from the U.K. Biobank showed.

Higher adherence to the MIND diet was associated with larger volumes of thalamus, putamen, pallidum, hippocampus, and accumbens and lower white matter hyperintensities, regardless of genetic predispositions of Alzheimer's disease, reported Changzheng Yuan, ScD, of Zhejiang University School of Medicine in Hangzhou, China, and Harvard T. H. Chan School of Public Health in Boston, and co-authors in .

"Our study discovered that adherence to the MIND diet showed beneficial associations with white matter hyperintensities and certain subcortical brain region volumes among middle-aged and older adults," Yuan and co-authors wrote.

"The main independent contributors of the MIND diet included higher intake of whole grains and olive oil, and lower intake of fast fried foods," they added.

The MIND diet emphasizes plant-based foods, limits intake of animal-based foods and those high in saturated fat, and promotes eating berries and leafy green vegetables. In postmortem brain tissue, components of the diet -- like green leafy vegetable intake -- have been inversely correlated with less Alzheimer's pathology.

Several observational studies have suggested that adhering to the MIND diet was linked with a lower risk of incident dementia in middle-aged and older adults. But whether diet influences cognition is not clear: the phase III MIND trial of overweight and obese people ages 65 to 84 showed no differences in cognition between the MIND diet versus mild caloric restriction over 3 years. And in a prospective Swedish study, midlife dietary habits were not tied to dementia incidence over a 20-year period.

Yuan and colleagues evaluated 26,466 participants who had brain MRI from 2014 to 2020 and a 15-point MIND score calculated from 24-hour diet recalls from 2009 to 2012. Mean age at recruitment from 2006 to 2010 was 55, and about half of participants (53.5%) were women. A subset of 2,963 participants (mean age 53) had a second imaging assessment between 2018 and 2022.

MIND diet scores were calculated based on intake of 10 healthy food groups (green leafy vegetables, other vegetables, berries, nuts, whole grains, beans, non-fried fish, non-fried poultry, olive oil, and wine) and five unhealthy food groups (red meats, butter and margarine, cheese, pastries and sweets, and fried or fast foods). Covariates included age, sex, ethnicity, deprivation, education, physical activity, smoking, and total energy intake.

While significant associations were seen in subcortical regions, the researchers did not find a significant relationship between MIND diet scores and total brain, white matter, or gray matter volumes. Links between the MIND diet and brain structure markers did not significantly differ by APOE4 status or Alzheimer's disease polygenic risk scores.

Over a median of 2.2 years, no significant association emerged between the MIND diet and longitudinal changes in brain structural markers in people who had two imaging assessments. These findings echoed that of the 3-year MIND trial, the researchers noted, and may be due to the relatively young age of participants in the U.K. Biobank substudy.

The highest intake of whole grains was associated with higher volumes of total brain, gray matter, and all subcortical regions investigated except for the amygdala, with beta coefficients ranging from 0.034 to 0.094, Yuan and co-authors pointed out.

"Similarly, using olive oil as the primary oil showed protective associations with several subcortical regions, including the thalamus, caudate, pallidum, and amygdala," they added.

The study has limitations, the researchers cautioned. U.K. Biobank participants might be healthier than the general population, and dietary data were self-reported. In addition, findings may have been influenced by residual confounding and reverse causality.

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