What to Eat to Reduce Your Risk of Alzheimer’s Disease

Would you like reduce your risk of cognitive impairment, Alzheimer’s disease, and dementia? Researchers from around the world have been studying a variety of different factors that might reduce these risks and keep the brain healthy.

Old news: The Mediterranean diet is beneficial

One factor that a number of studies have converged on is a Mediterranean-style diet. This diet includes:

• fish
• olive oil
• avocados
• fruits
• vegetables
• nuts
• beans
• whole grains
• red wine in moderation

Now, if you’re like me and you happen to like all these foods, then you have all the information you need to eat a brain-healthy diet. On the other hand, if you’re not crazy about everything on the list, perhaps you would rather eat only the most important components. Researchers have, in fact, been trying to determine the key parts of this diet for a number of years.

For example, one study published in 2015 and updated in 2018 compared healthy older adults who followed a Mediterranean diet with extra olive oil or extra nuts versus a control reduced-fat diet. The enhanced Mediterranean diet groups fared equally well, and both had better cognitive performance outcomes than the reduced-fat diet group.

No study, however, has been able to determine the critical components of the Mediterranean diet that makes it so good for your brain — until now.

The new study

Researchers at the National Institutes of Health published a study that evaluated the lifestyles of over 7,750 participants followed for five to 10 years. Participants filled out questionnaires to determine their eating habits, and had cognitive tests of memory, language, and attention administered over the phone. They used these data to determine the dietary factors most important in lowering your risk of cognitive impairment, as well as the dietary factors most important in lowering your risk of cognitive decline.

Cognitive impairment versus cognitive decline

Let’s take a moment to unpack these terms.

• Cognition is a shorthand way of saying thinking, memory, language, attention, visuospatial, and other mental abilities.
• Your risk of cognitive impairment is the risk that 10 years from now your cognition will be worse than your peers.
• Your risk of cognitive decline is the risk that 10 years from now, your cognition will be worse than it is now.

Fish helps you think — and keeps your thinking strong

What did the researchers find? Fish was the single most important dietary factor in lowering the risk of cognitive impairment. Vegetables were second best, and all other foods showed smaller, insignificant effects. Moreover, of all the foods evaluated, only fish was associated with a lower risk of cognitive decline. Eating fish lowered the risk of both cognitive impairment and cognitive decline.

The take-home lesson

To reduce your risk of cognitive impairment and decline, eat a Mediterranean-style diet including fish several times per week. There are lots of good fish to eat, including Atlantic mackerel, black sea bass, catfish, clams, cod, crab, crawfish, flounder, haddock, lobster, salmon, sardines, scallops, shrimp, skate, sole, squid, tilapia, trout, and canned light tuna. Just be careful about fish that may have high levels of mercury, such as swordfish and bigeye tuna; these fish should only be eaten occasionally. The FDA has a good guide to help you know the best fish to eat.

Your mother was right

Did your mother ever tell you that fish was good for you? Mine did. In fact, she always used to say, “Fish helps you think.” She knew it all along; it just took the scientific community 50 years to catch up to her and prove it.

(Andrew E. Budson, MD, is a contributor to Harvard Health Publications.)

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