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Changes in the brain can occur years before the first symptoms of Alzheimer's appear. These early brain changes suggest a possible window of opportunity to prevent or delay dementia symptoms. Scientists are looking at many possible ways to do this, including drugs, lifestyle changes, and combinations of these interventions. Unlike other risk factors for Alzheimer’s that we can’t change, such as age and genetics, people can control lifestyle choices such as diet, exercise, and cognitive training.
How could what we eat affect our brains? It’s possible that eating a certain diet affects biological mechanisms, such as oxidative stress and inflammation, that underlie Alzheimer’s. Or perhaps diet works indirectly by affecting other Alzheimer’s risk factors, such as diabetes, obesity, and heart disease. A new avenue of research focuses on the relationship between gut microbes—tiny organisms in the digestive system—and aging-related processes that lead to Alzheimer’s.
One diet that shows some promising evidence is the Mediterranean diet, which emphasizes fruits, vegetables, whole grains, legumes, fish and other seafood, unsaturated fats such as olive oils, and low amounts of red meat, eggs, and sweets. A variation called MIND (Mediterranean–DASH Intervention for Neurodegenerative Delay) incorporates the DASH (Dietary Approaches to Stop Hypertension) diet, which has been shown to lower high blood pressure, a risk factor for Alzheimer’s disease.
The MIND diet focuses on plant-based foods linked to dementia prevention. It encourages eating from 10 healthy food groups and limits foods from five unhealthy food groups:
*Be careful about how much alcohol you drink. How the body handles alcohol can change with age.
Some, but not all, observational studies—those in which individuals are observed or certain outcomes are measured, without treatment—have shown that the Mediterranean diet is associated with a lower risk for dementia. These studies compared cognitively normal people who ate a Mediterranean diet with those who ate a Western-style diet, which contains more red meat, saturated fats, and sugar.
Evidence supporting the MIND diet comes from observational studies of more than 900 dementia-free older adults, which showed that closely following the MIND diet was associated with a reduced risk of Alzheimer’s disease and a slower rate of cognitive decline.
Not all studies have shown a link between eating well and a boost in cognition. Overall, the evidence suggests, but does not prove, that following a Mediterranean or similar diet might help reduce the risk for Alzheimer’s dementia or slow cognitive decline. To find out more, scientists supported by NIA and other organizations are conducting clinical trials—considered the gold standard of medical proof—to shed more light on any cause and effect. (See a list of trials that are recruiting participants at the end of this article.)
Scientists aren’t sure why the Mediterranean diet might help the brain. This primarily plant-based diet has been shown to improve cardiovascular health, which may, in turn, reduce dementia risk. In contrast, the typical Western diet increases cardiovascular disease risk, possibly contributing to faster brain aging.
In addition, this diet might increase specific nutrients that may protect the brain through anti-inflammatory and antioxidant properties. It may also inhibit beta-amyloid deposits, which are found in the brains of people with Alzheimer’s or improve cellular metabolism in ways that protect against the disease.
