Two Healthy Diets May Reduce Brain ‘Plaques’ Tied to Alzheimer’s Risk

Elderly adults who eat plenty of leafy green vegetables, fish and other healthy fare may take years off their “brain age,” a new study suggests.

Researchers found that seniors with either of two healthy eating patterns — the Mediterranean and MIND diets — showed fewer brain “plaques,” abnormal protein clumps that are a hallmark of Alzheimer’s disease.

In fact, people with the highest Mediterranean or MIND scores had brains that were up to 18 years younger than their counterparts with more of a burger-and-fries diet.

Experts said the findings do not prove that spinach and fish will ward off dementia. But they do add to a growing body of evidence linking healthy eating to slower brain aging.

Lead researcher Puja Agarwal called the results “exciting,” because they suggest that even a simple dietary change could make a substantial difference.

Based on the findings, older people who eat, say, a cup of leafy greens a day could have a brain that’s four years younger, versus their peers who shun the likes of kale and spinach.

The study, published March 8 in Neurology, builds on past research into diet and dementia.

Both the Mediterranean and MIND diets have already been linked to slower mental decline and a lower risk of Alzheimer’s disease, the researchers said in background notes. Now the new findings connect the diets to fewer objective signs of Alzheimer’s — the plaques that begin to form in the brain years before dementia symptoms appear.

That strengthens the case that the eating patterns are truly associated with lower Alzheimer’s risk, according to Agarwal, an assistant professor at Rush University Medical College in Chicago.

“It also gives us a first view into the mechanisms,” she said.

That is, less accumulation of brain plaques may be one way the diets protect against Alzheimer’s — though, Agarwal said, it’s not yet clear how they might accomplish that.

The traditional Mediterranean diet — famously linked to lower risks of heart disease and stroke — is generally high in fish, olive oil, vegetables, beans, nuts and fiber-rich grains.

The MIND diet is very similar, but emphasizes leafy green vegetables and berries over other vegetables and fruit. That’s based on research tying those foods to better brain health.

Both diets, according to the Rush University researchers, are high in plant foods that have various nutrients and chemicals that can ease inflammation in the body and protect cells from damage.

Both diets are also notable for what they leave out: red meat, sugar and heavily processed foods.

The new findings are based on autopsied brain tissue from 581 participants in a long-running Rush study on memory and aging. When they entered the study, typically in their early 80s, they gave consent to donate their brains after death.

Each year, study participants complete detailed dietary questionnaires. Agarwal’s team used that information to give each of the 581 deceased participants a Mediterranean and a MIND diet “score.” The more their eating habits looked like those diets, the higher the scores.

Overall, the researchers found, participants who’d scored highest in Mediterranean-style eating had brains that, based on plaque buildup, were 18 years younger than those of participants with the lowest Mediterranean scores. The differences were similar, though somewhat smaller, when it came to MIND scores.

Certain foods stood out, too, Agarwal said. People who ate the most leafy greens — at least seven servings a week — spared themselves about 19 years of brain aging, versus their peers who ate no more than one serving a week.

Of course, people who eat healthfully may have advantages, like a higher income or more education. They may also have fewer chronic medical conditions, or do other things to support their health, like exercising and refraining from smoking.

Agarwal’s team accounted for as many of those factors as they could, and healthy eating was still strongly linked to a younger-looking brain.

The findings are “intriguing,” said Heather Snyder, vice president of medical and scientific relations at the Alzheimer’s Association.

“This study takes what we know about the link between nutrition and risk for cognitive decline a step further by looking at the specific brain changes that occur in Alzheimer’s disease,” said Snyder, who had no role in the study.

She noted that the Alzheimer’s Association is leading a two-year clinical trial that is testing whether a combination of lifestyle changes can slow cognitive decline in older adults. The MIND diet is part of that combo.

It’s not yet clear what the best lifestyle “recipe” is, according to Snyder. What is clear, she said, is that people should strive for a “heart-healthy diet that incorporates nutrients that our bodies and brains need to be at their best.”

The participants in the Rush study were asked about their eating habits in the past year. It’s not known, Agarwal said, if they’d eaten that way their whole lives, or made changes at some point.

Still, she said, “it’s never too late” to revamp your diet for the better.

More information

The Alzheimer’s Association has advice on healthy brain aging.

SOURCES: Puja Agarwal, PhD, MS, assistant professor, internal medicine, Rush University Medical College and Medical Center, Chicago; Heather Snyder, PhD, vice president, medical and scientific relations, Alzheimer’s Association, Chicago; Neurology, March 8, 2023, online