A diet combining elements of the Mediterranean diet with a diet designed to lower blood pressure may help slow some of the structural changes that occur as the brain ages, according to a study published online in the 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 has also been associated with less enlargement of the brain’s ventricles, fluid-filled spaces that tend to expand as brain tissue shrinks.
What is the MIND diet?
Mediterranean Dietary Approaches to Stop Hypertension Dietary Intervention in Neurodegenerative Delay, or MIND for short, has previously been associated with better cognitive health, researchers say.
Eating habits emphasize green leafy vegetables; other vegetables; berries; nut; whole grains; fish; beans; olive oil; and poultry, as well as 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 its cognitive benefits, its relationship to age-related changes in brain structure has remained less clear. These structural changes also apply to neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases.
Researchers have tracked brain changes for years
To investigate, researchers studied 1,647 middle-aged and older adults (mean age 60 at study start) from the Framingham Heart Study Offspring (FOS) cohort.
Participants underwent regular health assessments every 4 to 8 years. Starting in 1999, they also underwent brain MRI every 2 to 6 years.
Diet was assessed using at least one food frequency questionnaire (FFQ) completed during check-ups between 1991-5, 1995-8 and/or 1998-2001. Each participant also underwent at least two brain MRIs between 1999 and 2019 and showed no signs of stroke or dementia at the time of their first MRI.
The average MIND diet score was just below 7 out of a possible 15, with 15 representing the highest adherence.
Those in the top third of MIND diet adherence were more likely to be female and college-educated. They were also less likely to smoke or be obese.
They were also less likely to have diseases that can affect brain health, including 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, MRI scans showed the expected age-related changes in the entire group. These included decreases in total brain, gray matter, white matter, and hippocampal volumes.
At the same time, cerebrospinal fluid and ventricular volumes increased, as did white matter hyperintensities, which appear as bright spots on MRI scans and can indicate tissue damage.
However, people with higher MIND diet scores experienced slower gray matter loss.
Each 3-point increase in MIND diet score was associated with (0.279 cm³/year) slower gray matter loss. 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 delayed brain aging.
Berries and poultry stand out
Certain foods appeared to contribute more strongly to favorable associations.
Higher berry consumption was linked to a slower increase in ventricular volume. Poultry was also associated with slower ventricular enlargement, as well as slower gray matter decline.
In contrast, higher intake of sweets was associated with faster ventricular hypertrophy and greater hippocampal atrophy. Fried fast foods were also associated with a greater decrease in hippocampal volume.
“Antioxidant-rich foods recommended by MIND, such as berries, and high-quality protein sources like poultry may reduce oxidative stress and attenuate neuronal damage,” the researchers suggest. “Conversely, 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 discoveries were unexpected
Not all foods produced the expected pattern.
Higher whole grain consumption was associated with several adverse structural changes, including more rapid losses of gray matter and hippocampal volume, as well as more rapid ventricular hypertrophy.
Cheese showed the opposite trend. Greater cheese consumption was associated with slower declines in gray matter and hippocampal volume, less ventricular hypertrophy, and decreased white matter hyperintensities.
Benefits appear greater among older people
The overall associations remained consistent across several additional analyzes and were stronger in older participants.
The researchers say this could suggest that the MIND diet might be particularly relevant for people at higher risk of more rapid brain aging or those with greater variation in the rate of brain atrophy.
Stronger associations were also observed among participants who were more physically active and among those who were neither overweight nor obese.
This pattern raises the possibility that combining a brain-healthy diet with other healthy lifestyle habits could help reduce the risk of neurodegenerative disease, the researchers say.
Study cannot prove cause and effect
The results come from an observational study, so they cannot establish that the MIND diet directly causes the slower brain changes.
The researchers also note that meal frequency questionnaires rely 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.
Given that participants were predominantly white, the results 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 diet and support its role in strategies to slow neurodegeneration in aging populations.” »
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