Scientists found that older adults who closely followed one of these dietary patterns had fewer amyloid plaques and tau tangles in the brain than those that did not adhere strictly to the diets.
Alzheimer’s disease is a type of dementia that may involve abnormal amounts of protein-derived amyloid plaques and tau tangles that accumulate in the brain. These accumulated plaques and tangles may cause brain changes that lead to the development of the disease.
Although scientists don’t entirely understand the factors that lead to increases in plaques and tangles, some believe that diet may play a role.
However, a new study published on March 8 in the journal Neurology may have uncovered more clues about the relationship between diet and the buildup of these proteins associated with Alzheimer’s.
To conduct the experiment, scientists recruited 581 older adults with an average age of 84. The participants agreed to donate their brains after they died for scientific research on dementia.
Every year, the participants filled out questionnaires reporting what types of food and how much they ate from various categories.
On average, the participants died seven years after the start of the study. Before they died, 39% had a dementia diagnosis, and upon examination after death, 66% met the diagnostic criteria for Alzheimer’s disease.
The research team looked at the number of amyloid plaques and tau tangles in the deceased participant’s brains and compared what they found to the quality of their diet as reported in the yearly questionnaires.
After examining these comparisons and adjusting for factors like sex, educational level, total caloric intake, and genes linked to Alzheimer’s risk, the team found that participants who adhered more closely to the MIND diet — a way of eating certain foods and nutrients that can protect the brain — had plaque and tau tangle amounts that were similar to being 12 years younger than individuals who didn’t follow the diet as strictly.
Moreover, those who stuck closely to the Mediterranean diet had tau tangle and plaque amounts that were similar to being 18 years younger compared to people who didn’t adhere to the diet as rigorously.
The researchers also found that participants who ate seven or more servings of green leafy vegetables a week had plaque amounts that equated to being 19 years younger than those who ate one or fewer servings a week.
However, because the study primarily examined White, Non-Hispanic, and older participants, it’s unclear if these results would be the same in other populations. So, the study authors say more research is needed to understand the implications of the MIND and Mediterranean diet in different groups.
"While our research doesn’t prove that a healthy diet resulted in fewer brain deposits of amyloid plaques, also known as an indicator of Alzheimer’s disease, 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," says study author Puja Agarwal, Ph.D., of RUSH University in Chicago in a news release.
Agarwal also notes, "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."
What are MIND and Mediterranean diets?
The MIND diet blends two other popular diets — the Mediterranean diet and the DASH (Dietary Approaches to Stop Hypertension) diet. The MIND diet emphasizes consuming vegetables, berries, whole grains, nuts, fish, and poultry — while limiting the intake of red meat, cheese, butter and margarine, pastries and sweets, and fried or fast food.
In contrast, the Mediterranean diet is a dietary pattern inspired by the traditional eating habits of people in Mediterranean countries — such as Greece, Italy, and Spain.
This diet involves eating high amounts of whole grains, fruits, vegetables, legumes, nuts, and seeds, as well as olive oil as the primary source of fat. In addition, the Mediterranean diet allows moderate consumption of dairy products, fish, and poultry, while limiting red meat, processed foods, and sweets.
- NIH. What Happens to the Brain in Alzheimer's Disease?
- Newswise. MIND and Mediterranean Diets Associated with Fewer Alzheimer’s Plaques and Tangles.
- RUSH University. New MIND Diet May Significantly Protect Against Alzheimer’s Disease.
- American Heart Association. What is the Mediterranean Diet?