A Mediterranean diet — one that is rich in fish, vegetables and olive oil — may help ward off Alzheimer’s disease, a new study suggests.
An analysis of brain scans from more than 500 older adults revealed that seniors who consumed a Mediterranean diet were less likely to display brain shrinkage and high levels of the abnormal proteins that have been found to gunk up the brains of people diagnosed with Alzheimer’s, researchers reported in the medical journal Neurology.
“Following a Mediterranean-like diet could help slow down Alzheimer’s disease pathology and prevent cognitive decline,” said the study’s lead author, Tommaso Ballarini, a postdoctoral researcher at the German Center for Neurodegenerative Diseases in Bonn. “This is especially relevant for older people at higher risk for Alzheimer’s disease.”
“This study adds to the body of evidence concerning the protective effects of a healthy lifestyle on brain health and gives hopes for preventing dementia,” Ballarini said in an email.
Scientists have long known that the brains of patients with Alzheimer’s disease show shrinkage and display large quantities of two abnormal proteins: amyloid beta, which causes plaques to develop between nerve cells, and tau, which accumulates into tangles that clog the interiors of cells, eventually killing them.
For the new study, Ballarini and his colleagues recruited 512 seniors, average age 69, 343 of whom were at higher risk of developing Alzheimer’s either due to close relatives with the disease or declines in memory or thinking ability.
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The brains of all the seniors were scanned via MRI and cerebrospinal fluid samples were tested for levels of the two abnormal proteins. Data on diet came from a questionnaire that asked about foods consumed in the past month and each study participant received a score based on how often they ate healthy foods typical of the Mediterranean diet, such as fish, vegetables, legumes, fruit, whole grains and olive oil, and how often they consumed unhealthy foods, like red meat.
Thinking, or cognitive, abilities were assessed with a battery of tests that focused on five different areas, including language ability, memory and executive function. Executive function includes facilities such as judgement and the ability to focus and plan.
When the researchers analyzed the combined results of the brain scans, the cognitive tests and the diet scores along with demographic factors such as age, sex and education, they found that each point lower on the dietary score corresponded to almost an entire year of brain aging.
Moreover, those who had low dietary scores were more likely to have lower scores on memory tests and to have higher levels of amyloid and tau.
The research doesn’t explain how diet might affect brain health.
“This remains an intriguing open question,” Ballarini said. “Following a Mediterranean diet could act on specific mechanisms related to Alzheimer’s disease neuropathology, for example, by modulating neuroinflammation, or it could sustain brain health through systemic effects, for example, by fostering cardiovascular health.”
The main message of this study is that healthy lifestyles can help preserve cognition, said Dr. Oscar Lopez, a professor of neurology at the University of Pittsburgh School of Medicine.
What the study can’t tell is whether the diet is helping the brain or if it’s just a marker for an overall healthy lifestyle, Lopez said. “People who are eating healthy are more likely to see their doctors more often, to be better educated and to be involved with cognitively stimulating activities,” he added. “So it’s a constellation of activities that happen around a healthy diet.”
Nevertheless, Lopez said, eating a Mediterranean diet has been shown to be good for you in other ways, so even if it weren’t proven to preserve brain function, it’s going to keep you healthy.
