Mediterranean diet may reduce risk of dementia and Alzheimer’s, science shows

A diet rich in seafood, fruits, vegetables, nuts and olive oil may lower the risk of dementia, according to a new study.

An analysis of data from more than 60,000 seniors found that choosing a Mediterranean diet reduced a person’s chance of developing dementia by almost a quarter, even among people with genes that put it at greater risk, according to the Am Report published Monday in the Medical journal BMC Medicine.

“The main message of this study is that even for individuals with a higher genetic risk, eating a more Mediterranean diet could reduce the likelihood of developing dementia,” said the study’s lead author Oliver Shannon, Lecturer in Human Sciences Nutrition and Aging at Newcastle University.

Among people whose diets were least similar to a Mediterranean diet, “about 17 out of every 1,000 people developed dementia during the approximately nine-year follow-up of the study,” Shannon said in an email.

In contrast, among people whose diets most closely resembled a Mediterranean diet, “only about 12 people out of 1,000 would develop dementia,” he added.

What is a Mediterranean diet?

A Mediterranean diet is replete with healthy plant-based foods like vegetables, nuts, and legumes. It is rich in whole grains, fruits, olive oil and fish.

People in the study also typically ate less red or processed meat, sweets and pastries, and drank fewer sugar-sweetened beverages, Shannon said.

Previous studies have been mixed on whether a Mediterranean diet can help stave off dementia. In fact, a study published in October examining medical records from 28,025 Swedes found that diet does not protect against dementia. In contrast, another study published in May involving nearly 2,000 older adults found that a diet high in pro-inflammatory foods — as opposed to the Mediterranean diet, which appears to be anti-inflammatory — was associated with faster brain aging who was visible on MRI scans and a higher risk of developing dementia.

Choosing a Mediterranean diet reduces a person’s chance of developing dementia by almost a quarter.Lauren Segal / The New York Times on Redux

To look more closely at the impact of a Mediterranean diet on dementia risk, Shannon and his colleagues turned to the UK Biobank, which recruited men and women aged 4 to 69 from across England, Scotland and Wales in 2006-2010. The prospective study currently has more than half a million participants.

Recruits completed a touchscreen questionnaire, participated in an oral interview, and provided biological samples and physical function measurements. Later, recruits received scans, were evaluated for multiple health outcomes, and provided information about their diet, some at multiple times during the study. The biobank was able to track the participants’ health status through linked electronic medical records.

An additional dimension of the new study was the inclusion of genetic information in the form of an Alzheimer’s risk score developed in previous research.

“The risk score was created using approximately 250,000 individual genetic variants that have been linked to Alzheimer’s disease, the most common form of dementia,” explained Shannon.

For the new study, the researchers focused on 60,298 participants who were in their 60s at the time of recruitment. During a mean follow-up of nine years, 882 people developed dementia.

When the researchers processed their data, they found that people whose food intake most closely resembled the Mediterranean diet were 23% less likely to develop dementia in the years covered by the study.

The new research adds to the mounting evidence that diet can affect dementia risk even in people who are at higher risk because of their genes, said Dr. Thomas Wisniewski, professor of neurology, pathology and psychiatry and director of the Alzheimer’s Disease Research Center and the Center for Cognitive Neurology at NYU Langone.

“This study, with really good numbers and a pretty sizeable effect size, shows that following a Mediterranean diet is indeed brain-protective,” Wisniewski said. “This is positive news and certainly something that anyone can do with relative ease. So that’s good news.”

Reducing the risk of dementia

Diet “is one of those lifestyle things that I discuss with all my patients,” Wisniewski said. “The other thing we usually discuss with patients is the importance of staying physically and mentally active.”

Other important ways to reduce the risk of dementia include:

These are all actions anyone can take to keep their brain healthy and reduce their risk of developing dementia,” Shannon said.

The new study found a nearly a quarter reduction in the risk of dementia, Wisniewski said. “That’s a pretty big risk mitigation by doing something that’s not that challenging,” he added.

While it’s not known exactly how the Mediterranean diet might reduce dementia risk, it likely has multiple effects ranging from reducing antioxidants to curbing inflammation and improving the status of the microbiome, Wisniewski said.

Without good drugs to treat dementia, experts have focused on lifestyle factors that may have some impact on risk, said Dr. Emily Rogalski, a cognitive neuroscientist and professor of psychiatry and behavioral sciences at Northwestern University’s Feinberg School of Medicine.

At the moment, it’s unclear if there’s a point when it’s too late to protect yourself against dementia.

“But giving up and saying it’s too late is probably not the right attitude,” she said.

“We used to think that we were born with all the brain cells that we would ever have and that the brain isn’t as plastic or malleable or resilient,” Rogalski said. “We have learned over the past few decades that there is room for adjustment and change.”

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