Plant-Based Diets: Lowering Dementia and Alzheimer’s Risk to Slow Brain Aging

A study published on April 8, 2026, in the journal Neurology® indicates that adhering to a high-quality plant-based diet may be linked to a lower risk of developing Alzheimer’s disease and other forms of dementia. The research suggests that these cognitive benefits can be realized even when individuals adopt healthier eating habits later in life, specifically in their late 50s, and 60s.

The study followed nearly 93,000 adults over an average period of 11 years. The participant group was diverse, including White, African American, Latino, Japanese American, and Native Hawaiian individuals, with an average starting age of 59. During the observation period, more than 21,000 of these participants developed dementia or Alzheimer’s disease.

Distinguishing Between Plant-Based Diet Qualities

Researchers emphasized that not all plant-based diets provide the same cognitive protections. The study distinguished between a healthful plant-based diet and an unhealthful one, noting that simply prioritizing plants over animal products like meat, milk, and eggs is not enough to ensure brain health.

A healthful plant-based diet is characterized by the consumption of whole grains, fruits, vegetables, nuts, legumes, and vegetable oils, as well as beverages such as coffee and tea.

In contrast, an unhealthful plant-based diet consists of higher amounts of refined grains, sugary foods and drinks, fruit juice, and potatoes. These items are frequently consumed as part of processed meals or fast food.

Impact on Dementia Risk

The findings revealed a significant correlation between diet quality and the likelihood of cognitive impairment. Older adults who successfully reduced the intake of unhealthy foods over a decade showed an 11% lower risk of dementia and Alzheimer’s disease compared to those whose diets remained unchanged.

Conversely, the study found that individuals who increased their consumption of unhealthy plant-based options, such as foods with added sugars and refined grains, were approximately 25% more likely to develop some form of dementia by the end of the 10-year period.

The research highlighted that diet changes over time directly influenced risk levels. Participants who shifted their eating habits away from unhealthful plant-based foods saw a decrease in risk, while those who shifted toward them saw an increase.

Clinical Context and Expert Perspectives

The study’s authors noted that while plant-based diets are already known to help reduce risks for high blood pressure and diabetes, their specific impact on Alzheimer’s and other dementias has been less understood.

Plant-based diets have been shown to be beneficial in reducing the risk of diseases like diabetes and high blood pressure, but less is known about the risk of Alzheimer’s disease and other dementias

Song Yi Park, PhD, University of Hawaii at Manoa

Unhee Lim, a professor of population sciences at the University of Hawaii Cancer Center and senior author of the study, emphasized that the window for making these lifestyle changes remains open well into older age.

It’s never too late to start eating healthy to lower the risk of Alzheimer’s disease and related dementias

Unhee Lim, University of Hawaii Cancer Center

Dr. David Katz, a specialist in preventive and lifestyle medicine, stated that the findings indicate that both a plant-predominant diet and high diet quality are essential for protecting brain function during the aging process.

Dietary Definitions and Limitations

The researchers clarified that the study did not specifically focus on vegan or vegetarian diets. While vegans follow a plant-based diet, the study noted that a person could identify as vegan while still consuming ultraprocessed, fat-filled, and sugary foods—such as frozen waffles with fake maple syrup—which are known to harm health.

This distinction is supported by broader medical literature, which notes that plant-based and vegan diets are not synonymous. While consuming a plant-based diet can be a low-risk and beneficial lifestyle change for maintaining cognitive health, the quality of the plant foods consumed is the determining factor in preventing cognitive aging.

The study accounted for several variables, including age, diabetes, and physical activity, to isolate the effects of diet on dementia risk.