Could the Mediterranean diet reduce dementia risk?

• A study finds that the health benefits of a Mediterranean diet may include a reduced chance of developing dementia and memory loss.
• Specifically, the diet appears to lower the level of amyloid and tau proteins that are linked with dementia.
• People following the Mediterranean diet scored better on memory tests than those who were not following the diet.

Previous research has determined that a Mediterranean diet can benefit heart health and aid in weight loss. Now, a new study finds that it may also help reduce the risk of dementia and cognitive decline.

The study has shown that a Mediterranean diet can help prevent the buildup of two proteins and brain-volume shrinkage that are associated with Alzheimer’s disease.

The first of these proteins, amyloid protein, forms plaques in the brain, whereas the second, tau protein, forms tangles. Both are present in the brains of people with Alzheimer’s, though they are not uncommon in the brains of healthy older people, too.

“These results add to the body of evidence that shows what you eat may influence your memory skills later on,” says study author Tommaso Ballarini, Ph.D., of the German Center for Neurodegenerative Diseases in Bonn, Germany. He adds:

The scientists published the study online in the May 5, 2021, issue of Neurology, a journal of the American Academy of Neurology.

The Mediterranean diet

Studies have linked good health with the foods that people living in Greece, Spain, and Italy ate before the 1960s. The Mediterranean diet is based on their food preferences.

This diet consists primarily of vegetables and fruits, nuts and seeds, legumes, potatoes, whole grain foods, seafood, extra virgin olive oil, and wine in moderation. A person following the diet can also occasionally eat poultry, eggs, and dairy products, such as yogurt and cheese.

The food types largely missing from a Mediterranean diet are red meat, added sugar, refined grains and oils, and processed foods.

Dietitian at Cleveland Clinic Kristin Kirkpatrick told Medical News Today that the contents of a Mediterranean diet contribute beneficial “omega-3 fatty acids, polyphenols, specific minerals, fiber, and protein” that “may support the brain’s health and protection throughout the years.”

However, Kirkpatrick cautions that, “A diet, even one with strong clinical data on its benefit, is only as healthy as the individuals who choose its structure.”

She notes the importance of sensible portion sizes and warns against the “consumption of processed foods that are marketed as heart-healthy or contain the components seen in a traditional Mediterranean approach.”

Finding associations

For the current study, the researchers recruited 512 individuals from the German Center for Neurodegenerative Diseases’ Longitudinal Cognitive Impairment and Dementia Study. Assessments of the participants revealed that 343 were at a higher risk of developing Alzheimer’s disease while the remaining 169 people were “cognitively normal.”

The participants completed questionnaires regarding the food they ate the previous month. The researchers asked them to record their intake of 148 specific food items. Individuals received scores for their diet quality, with the people who had eaten a diet most closely resembling a Mediterranean diet receiving the highest scores on a scale of 1 to 9.

An obvious limitation of the study is that people self-reported their eating habits, so errors or misrepresentations are possible.

Individuals also took cognitive tests designed to detect the progression of Alzheimer’s disease. The tests assessed five areas: memory, working memory, language, executive functions, and visuospatial abilities. MRI brain scans determined each individual’s brain volume.

Finally, the researchers analyzed spinal fluid from a subsample of 226 participants who gave their consent, assessing the presence and amounts of the two biomarker proteins: amyloid and tau.

After adjusting for sex, age, and education, the scientists identified several clear links between better cognitive health and a Mediterranean diet.

They reported that:

• Every dietary grade point lower than 9 was associated with nearly 1 year of the brain aging that occurs in Alzheimer’s disease progression.
• The participants who most closely followed the Mediterranean diet had fewer amyloid and tau protein biomarkers in their spinal fluid than those who had lower dietary scores.
• People who followed the Mediterranean diet scored better on memory tests than people who did not.

According to Dr. Ballarini: “More research is needed to show the mechanism by which a Mediterranean diet protects the brain from protein buildup and loss of brain function, but findings suggest that people may reduce their risk for developing Alzheimer’s by incorporating more elements of the Mediterranean diet into their daily diets.”

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