If you’re at risk of Alzheimer’s, these dietary habits can help, study finds

When it comes to dementia risk, certain factors, such as genetics, are out of your control. However, plenty of research suggests lifestyle behaviors – things you can change – may help improve your chances of staying sharp as you age. In a new study, people with an elevated risk of dementia were less likely to develop the condition if they followed a healthy dietary pattern, particularly a less inflammatory one.

For the study, published in JAMA Network Open, researchers at Karolinska Institutet in Sweden followed nearly 1,900 adults aged 60-plus for 15 years, 240 of whom developed dementia during this time. Participants had their blood tested for proteins that indicate dementia- and Alzheimer’s-related brain changes (known as biomarkers) and also completed questionnaires about their eating habits on several occasions. The researchers then scored the quality of their diets based on three metrics:

• Alternate Mediterranean Diet, which measures how closely a diet aligns with Mediterranean-diet pillars, such as eating ample plants and fish and limiting red meat.

• Alternative Healthy Eating Index, which rates a diet based on its inclusion of foods that lower chronic disease risk and exclusion of items that raise it

• Reversed Empirical Dietary Inflammatory Index, which captures the inflammatory potential of a diet by assigning weighted scores to certain foods and drinks based on their ties to blood markers of inflammation.

By studying specific kinds of healthy diet patterns, the researchers could determine whether certain ones might be more important for people at different risk levels. And a distinction emerged: “The dietary pattern with lower inflammatory potential showed the most consistent associations (with lower dementia risk) among people with elevated biomarker levels,” Anja Mrhar, first author on the study and guest researcher at Karolinska Institutet, said in an email.

More specifically, the results showed that those with high p-tau217 – a protein in the blood that’s indicative of Alzheimer’s pathology – who followed a low-inflammation diet had a 29 % lower risk of dementia than those who had different eating patterns. And the researchers found nearly the same for people with biomarkers related to more general neurodegeneration: high glial fibrillary acidic protein, which is a measure of neuroinflammation, and high neurofilament light chain, a marker of nerve cell injury.

“The wonderful thing about this is, we’re saying, even for people who may have neuronal loss, (dementia) isn’t destiny,” said Allison B. Reiss, associate professor of medicine at NYU Grossman Long Island School of Medicine, who was not involved in the research.

Still, the study has limitations. It does not prove that diet can cause or prevent dementia; researchers observed participants but did not test the effects of a dietary intervention. It also relied on people to self-report their eating habits, which leaves room for error, and it lacked racial or ethnic diversity, Reiss said, which could limit its generalizability.

Why a less-inflammatory diet could help those at risk of dementia

There’s a substantial body of research showing that healthy diets, like the plant-forward Mediterranean diet, are associated with better cognition and lower dementia risk. Specific diets like the DASH (Dietary Approaches to Stop Hypertension) and MIND diet – which combines DASH with the Mediterranean diet – have also been linked with lower risk of experiencing cognitive decline and developing Alzheimer’s disease, respectively.

Other research, like the new study, goes a step further, suggesting that the upsides of diet might still be pertinent even in those people who are at high dementia risk. A recent study found that those who carry the APOE4 genetic variation (a risk factor for Alzheimer’s you are born with) may benefit most from adhering to a Mediterranean diet.

The JAMA study didn’t dig into why a less-inflammatory diet, in particular, may be linked to reduced dementia risk, but other research increasingly points to inflammation as a driving force in the condition.

Inflammation throughout the body often increases with age and as health conditions, such as high cholesterol and Type 2 diabetes, stack up, said Cyrus A. Raji, an associate professor of radiology and neurology at WashU Medicine who was not involved in the new study. “Inflammation may then make the brain more vulnerable to damage caused by misfolded proteins like amyloid and tau.”

A lower-inflammation diet could support the brain, and perhaps especially when the early changes that lead to dementia are already underway.

Without knowing your blood biomarkers, you can tell if you’re at increased risk for dementia by looking at family history, Reiss said. But ultimately, there’s little reason to go searching, she emphasized, as anyone can benefit from eating in a low-inflammatory way. This kind of diet is known to support other body parts such as your heart and liver too, Reiss pointed out, “and all our organs are interrelated and interdependent.”

In practice, a low-inflammatory diet looks similar to a Mediterranean-style diet or healthy diet based on nutrition guidelines – both of which were linked to reduced dementia risk in the study, particularly in those with lower biomarker levels, Mrhar said. And all of these diets may also benefit the brain in people across risk levels for reasons beyond inflammation, for instance by increasing insulin sensitivity or improving vascular health.

How to eat for long-term

brain health

The takeaway is that all three dietary patterns in the study were tied to lower dementia risk across groups, and each reflects a broad way of eating that you can adapt to your lifestyle. Even the inflammation-specific rEDII shouldn’t be viewed as a prescribed diet, Mrhar said. It’s an index for assessing diet on the whole, so interpreting it as a simple checklist of pro- and anti-inflammatory foods may not be helpful, much less practical.

Instead, experts suggested focusing on overall healthy eating patterns:

• Eat more fruits and vegetables, in whatever way is easiest or tastiest. Reiss pointed out that fresh or frozen options are both great, and it’s always better to eat them vs. not, so feel free to prepare them however you like. Or, she said, use a mom trick on yourself and hide them in other foods you enjoy (e.g., zucchini in baked goods, cooked carrots in tomato sauce).

• Limit ultra-processed foods to the extent you can. Packaged foods that have endured a long processing journey – ones that don’t resemble anything in nature, like refined grains and sugary drinks – tend to be pro-inflammatory, Raji said, and generally offer fewer healthy nutrients and are less satiating than unprocessed ones. However they’re also among the cheapest, most convenient foods. “It can feel like the option is to microwave your TV dinner or be a master chef every night,” Reiss said. “You want to try to find the best medium.”