In a cohort of deceased older adults, those who had adhered to the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) and Mediterranean diets for nearly a decade before death had less global Alzheimer’s disease–related pathology, primarily less beta-amyloid, at autopsy.
Those who most closely followed these diets had almost 40% lower odds of having an Alzheimer’s disease diagnosis at death. The findings offer one mechanism by which healthy diets protect cognition.
“While our research doesn’t prove that a healthy diet resulted in fewer brain deposits of amyloid plaques ... we know there is a relationship, and following the MIND and Mediterranean diets may be one way that people can improve their brain health and protect cognition as they age,” study investigator Puja Agarwal, PhD, of RUSH University Medical Center in Chicago, said in a statement.
The study was published online in Neurology.
Green leafy veggies key
The MIND diet was pioneered by the late Martha Clare Morris, ScD, a Rush nutritional epidemiologist, who died of cancer in 2020 at age 64.
Although similar, the Mediterranean diet recommends vegetables, fruit, and three or more servings of fish per week, whereas the MIND diet prioritizes green leafy vegetables, such as spinach, kale, and collard greens, along with other vegetables. The MIND diet also prioritizes berries over other fruit and recommends one or more servings of fish per week. Both diets recommend small amounts of wine.
The current study focused on 581 older adults who died while participating in the Rush Memory and Aging Project (MAP). All participants agreed to undergo annual clinical evaluations and brain autopsy after death.
Participants completed annual food frequency questionnaires beginning at a mean age of 84. The mean age at death was 91. Mean follow-up was 6.8 years.
Around the time of death, 224 participants (39%) had a diagnosis of clinical dementia, and 383 participants (66%) had a pathologic Alzheimer’s disease diagnosis at time of death.
The researchers used a series of regression analyses to investigate the MIND and Mediterranean diets and dietary components associated with Alzheimer’s disease pathology. They controlled for age at death, sex, education, APO-epsilon 4 status, and total calories.
Overall, both diets were significantly associated with lower global Alzheimer’s disease pathology (MIND: beta = –0.022, P = .034; and Mediterranean: beta = –0.007, P = .039) – specifically, with less beta-amyloid (MIND: beta = –0.068, P = .050; and Mediterranean: beta = –0.040, P = .004).
The findings persisted when the analysis was further adjusted for physical activity, smoking, and vascular disease burden and when participants with mild cognitive impairment or dementia at the baseline dietary assessment were excluded.
Individuals who most closely followed the Mediterranean diet had average beta-amyloid load similar to being 18 years younger than peers with the lowest adherence. And those who most closely followed the MIND diet had average beta-amyloid amounts similar to being 12 years younger than those with the lowest adherence.
A MIND diet score 1 point higher corresponded to typical plaque deposition of participants who are 4.25 years younger in age.
Regarding individual dietary components, those who ate seven or more servings of green leafy vegetables weekly had less global Alzheimer’s disease pathology than peers who ate one or fewer (beta = –0.115, P = .0038). Those who ate seven or more servings per week had plaque amounts in their brains corresponding to being almost 19 years younger in comparison with those who ate the fewest servings per week.
“Our finding that eating more green leafy vegetables is in itself associated with fewer signs of Alzheimer’s disease in the brain is intriguing enough for people to consider adding more of these vegetables to their diet,” Dr. Agarwal said in the news release.
Previous data from the MAP cohort showed that adherence to the MIND diet can improve memory and thinking skills of older adults, even in the presence of Alzheimer’s disease pathology.