The Exact Foods Linked to Lower Dementia Risk in New Study

A study tracking nearly 93,000 adults for more than a decade found that what kind of plant-based diet someone eats matters far more than simply eating more plants.

People who ate a healthy version of that diet had a meaningfully lower risk of developing dementia — even if they didn't start eating that way until their 60s.

What the Study Actually Measured

Researchers published the findings April 8, 2026, in Neurology, the medical journal of the American Academy of Neurology, according to CNN's reporting on the study.

The study followed 92,849 adults with an average starting age of 59, drawn from a diverse group that included African American, Japanese American, Latino, Native Hawaiian, and white participants. Over roughly 11 years of follow-up, 21,478 of them developed Alzheimer's disease or another form of dementia.

Rather than simply comparing vegetarians to meat-eaters, researchers split participants into three categories: an overall plant-based diet score, a healthy plant-based diet emphasizing whole foods, and an unhealthy plant-based diet built around refined grains and added sugar.

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Which Foods Actually Made the Difference

The distinction that mattered wasn't whether food came from a plant. It was which plant foods, specifically.

A healthy plant-based diet in the study included whole grains, fruits, vegetables, nuts, legumes, vegetable oils, and beverages like tea and coffee, according to the American Academy of Neurology's Brain & Life publication summarizing the research.

An unhealthy plant-based diet, by contrast, leaned on refined grains, sugary foods and drinks, fruit juice, and potatoes — often eaten as part of fast food or heavily processed meals. Critically, both categories still technically counted as "plant-based" under a simple vegetarian-versus-not measure, which is exactly the distinction the researchers were trying to capture.

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How Much the Difference Actually Mattered

The numbers behind the headline finding are more specific than "plants are good for your brain."

Participants with the highest overall plant-based diet scores had a 12% lower risk of Alzheimer's disease and related dementias compared with those who scored lowest, according to AARP's coverage of the findings.

After accounting for factors like age, physical activity, and diabetes, the healthy and unhealthy plant-based categories pulled risk in opposite directions: those following the healthy version more closely showed lower dementia risk, while those eating more of the unhealthy version showed higher risk.

Why Starting Later in Life Still Counted

One of the study's more practical findings is that this isn't only about lifelong eating habits established decades earlier.

Lead author Song-Yi Park, an associate researcher involved in the study, noted that adopting a plant-based diet — even starting at an older age — was associated with lower dementia risk, while continuing to eat a low-quality plant-based diet was not protective regardless of when it started.

Participants whose diets shifted toward the unhealthy plant-based pattern over the course of the study saw their risk increase. Those who moved away from that pattern, even partway through the study period, saw their risk decrease.

What the Researchers Are Careful to Note

The study's authors and outside experts have flagged real limitations alongside the headline result.

The research relied on self-reported food questionnaires, which carry a known risk of inaccuracy since participants may not recall their actual eating patterns precisely over long stretches of time.

Researchers have also been explicit that the study is observational, meaning it can show a strong association between diet quality and dementia risk without proving that diet changes directly caused the difference. The large sample size and 11-year follow-up period are what give the findings their weight despite that limitation, and the results align with earlier research on the Mediterranean and MIND diets, both of which similarly emphasize whole, minimally processed foods.

Key Takeaways

• A study of 92,849 adults, published April 8, 2026 in Neurology, tracked diet and dementia risk over 11 years.

• 21,478 participants developed Alzheimer's disease or another dementia during the study.

• People with the highest plant-based diet scores had a 12% lower risk of dementia than those with the lowest.

• A healthy plant-based diet (whole grains, fruits, vegetables, nuts, legumes) was linked to lower risk; an unhealthy version (refined grains, sugary drinks, fruit juice) was linked to higher risk.

• Starting a healthy plant-based diet later in life, even in one's 60s, was still associated with reduced dementia risk.

Sources

• CNN — Eating More Plants Linked to Lower Risk of Dementia, Even in Older Age

• Brain & Life (American Academy of Neurology) — Healthy Plant-Based Diet May Lower Dementia Risk

• AARP — Healthy Plant-Based Diets May Lower Dementia Risk

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