A diet that combines elements of the Mediterranean diet with an eating plan designed to lower blood pressure may help slow some of the structural changes that occur as the brain ages, according to research published online in the journal Journal of Neurology Neurosurgery and Psychiatry.
Greater adherence to the MIND diet was associated with less loss of brain tissue over time, particularly gray matter, which plays an important role in memory, learning, decision making, and information processing. It was also associated with less enlargement of the brain’s ventricles, fluid-filled spaces that tend to grow as brain tissue shrinks.
What is the MIND diet?
Mediterranean dietary approaches to stopping hypertension, the Intervention Diet for Neurodegenerative Delay, or MIND for short, have previously been associated with better cognitive health, according to researchers.
The dietary pattern emphasizes leafy green vegetables; other vegetables; berries; balls; whole grains; fish; beans; olive oil; and poultry, along with moderate consumption of wine. It also recommends limiting butter/margarine, cheese, red meat, pastries/sweets, and fried fast foods.
Although previous research has linked the MIND diet to cognitive benefits, its relationship to age-related changes in brain structure remains less clear. These structural changes are also relevant to neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases.
Researchers tracked brain changes for years
To investigate, researchers studied 1,647 middle-aged and older adults (average age 60 at baseline) from the Framingham Heart Study Offspring (FOS) cohort.
Participants underwent regular health assessments every 4 to 8 years. Starting in 1999, they also had brain MRIs every 2 to 6 years.
Diet was assessed by at least one food frequency questionnaire (FFQ) completed during follow-ups between 1991-5, 1995-8 and/or 1998-2001. Each participant also underwent at least 2 brain MRI evaluations between 1999 and 2019 and showed no evidence of stroke or dementia at the time of their first MRI.
The average MIND diet score was just under 7 out of a possible 15, with 15 representing the strongest adherence.
People in the top third of adherence to the MIND diet were more likely to be women and have a college education. They were also less likely to smoke or be obese.
They were also less likely to have conditions that could affect brain health, such as type 2 diabetes, high blood pressure and cardiovascular disease.
Higher MIND scores linked to slower gray matter loss
Over an average follow-up period of 12 years, MRIs showed the expected age-related changes in the entire group. These included decreases in total brain, gray matter, white matter, and hippocampus volumes.
At the same time, cerebrospinal fluid and ventricle volumes increased, as did white matter hyperintensities, which appear as bright spots on MRIs and may indicate tissue damage.
However, people with higher scores on the MIND diet experienced slower gray matter loss.
Each 3-point increase in the MIND diet score was associated with slower gray matter loss (0.279 cm³/year). According to the researchers, this corresponded to 20% less age-related decline and the equivalent of 2.5 years of delay in brain aging.
A similar pattern appeared in ventricular enlargement. Each 3-point increase in MIND diet score was associated with a slower expansion of total ventricular volume of -0.071 cm³/year, equivalent to 8% less tissue loss and approximately 1 year of delay in brain aging.
Berries and poultry stand out
Some foods appeared to contribute more strongly to the favorable associations.
Higher berry intake was associated with slower increases in ventricular volume. Poultry was also associated with slower ventricular enlargement, along with slower gray matter decline.
In contrast, higher sweet consumption was associated with faster ventricular enlargement and greater hippocampal atrophy. Fried fast foods were also associated with a greater decrease in hippocampal volume.
“Foods rich in antioxidants, such as berries, and high-quality protein sources, such as poultry, recommended by MIND, can reduce oxidative stress and mitigate neuronal damage,” the researchers suggest. “In contrast, fried fast foods, often high in unhealthy fats, trans fats, and advanced glycation end products, may contribute to inflammation and vascular damage,” they add.
Some findings were unexpected
Not all foods produced the expected pattern.
Higher whole grain intake was associated with several unfavorable structural changes, including more rapid losses of gray matter and hippocampal volume, as well as more rapid ventricular enlargement.
Cheese showed the opposite pattern. Greater cheese intake was associated with slower decreases in gray matter and hippocampal volume, less ventricular enlargement, and fewer white matter hyperintensities.
The benefits seemed greater in older adults
The overall associations remained consistent in several additional analyzes and were stronger among older participants.
The researchers say this may suggest that the MIND diet could be especially relevant for people at higher risk of faster brain aging or those who show greater variation in the rate of brain atrophy.
Stronger associations were also seen among participants who were more physically active and among those who were not overweight or obese.
That pattern raises the possibility that combining a brain-healthy diet with other healthy lifestyle habits could help reduce the risk of neurodegenerative diseases, the researchers say.
The study cannot prove cause and effect
The findings come from an observational study, so they cannot establish that the MIND diet directly caused the slower brain changes.
The researchers also note that food frequency questionnaires depend on participants accurately remembering what they ate, which can introduce recall bias.
They also could not rule out mild cognitive impairment at the time of the first MRI, changes in diet over time, or the influence of genetic risk factors.
Because the participants were predominantly white, the findings may not apply equally to people of other ethnic backgrounds.
Still, the researchers conclude: “These findings reinforce the potential of the MIND diet as a brain-healthy dietary pattern and support its role in strategies aimed at curbing neurodegeneration in aging populations.”