Dr. Shahar Madjar
By Dr. SHAHAR MADJAR
Feeling forgetful? Have an aunt or a grandpa who “isn’t all there”? Many people worry they may have dementia or that they will develop Alzheimer’s disease. What if you could reduce your risk with simple changes to your diet?
An August study published in Nature Medicine by researchers from Mass General Brigham, led by Yuxi Liu, attempted to answer the question. Their goal was to test whether there is a link between diet and dementia and whether following the Mediterranean diet could prevent Alzheimer’s disease.
I will briefly describe how the study was performed, explain what dementia and Alzheimer’s disease are and conclude with the main findings.
The researchers used data from two large U.S. cohort studies: the Nurses’ Health Study (more than 4,200 women) and the Health Professionals Follow-Up Study (about 1,500 men). Participants were followed for decades. They completed food questionnaires, their genetic risk for Alzheimer’s and dementia was assessed, and their cognitive decline was measured using telephone-based tests.
For those unfamiliar with the subject, here is a crash course on dementia: Dementia isn’t a single disease but a group of symptoms — problems with memory, thinking, judgment and the ability to carry out daily activities — that develop when the brain is damaged and no longer works properly.
Alzheimer’s disease is the most common cause of dementia. In Alzheimer’s, the brain builds up abnormal proteins called amyloid plaques and Tau tangles, which make it harder for brain cells to communicate. Amyloid proteins stick together outside brain cells and block communication between neurons, while Tau proteins — which normally help stabilize the internal “skeleton” of brain cells — begin to twist, clump and tangle inside the cells.
Many of the affected cells eventually die, leading over time to memory loss, confusion and personality changes.
Several genes may predispose a person to Alzheimer’s disease. The most important is APOE4 gene, E4 for short. People can have zero, one or two copies of E4. Zero copies confer an average risk, one copy (inherited from one parent) raises the risk and two copies (one from each parent) raise risk by about eight to 12 times. A higher risk doesn’t mean you are destined to develop dementia — with two E4 copies, the risk of Alzheimer’s disease is roughly 50% to 60% by age 85.
The findings in Yuxi Liu’s study are striking: the Mediterranean diet was associated with a lower risk of dementia and slower cognitive decline across the board. The effect was strongest in people at the highest genetic risk, especially those who carried two copies of E4.
The Mediterranean diet was also correlated with healthier patterns in the body metabolites — small molecules the body makes as it digests food and runs its daily chemistry. These metabolites are like “smoke signals” of the body’s chemistry.
The study showed that while E4 genes make the “smoke” thicker, the Mediterranean diet helps “clear the air,” lowering the buildup of harmful signals.
How significant was the effect of the Mediterranean diet? Across all participants, those with higher adherence to the Mediterranean diet had a 23% lower risk of developing dementia compared to those with low adherence. The high-MedDiet group also had the equivalent of being two to three years younger in brain aging over the follow-up period.
In patients with two E4 copies, the Mediterranean diet had even greater effect — about a 40% reduction in dementia risk.
There are a few limitations to the study: participants were mostly European and fairly well educated (nurses and doctors), so the findings may not apply to the general population. Also, this was an observational study, which makes it difficult to prove a cause-and-effect relationship between the Mediterranean diet and dementia.
Still, the associations between the Mediterranean diet and reduced risk of dementia are strong, especially in people at greater genetic risk.
Want to keep a clear mind? Fill most of your plate with plants, use olive oil instead of butter, choose fish over red meat, and save sweets and processed foods for special occasions.
Editor’s note
: Shahar Madjar, MD, MBA, is a urologist and an author. He practices in Michigan, at Schoolcraft Memorial Hospital in Manistique, and in Baraga County Memorial Hospital in L’Anse. Find his books on Amazon or contact him at smadjar@yahoo.com.
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