LONDON — Research scientist Emma Nichols presented findings from a cross-national study on dementia risk factors at the Alzheimer’s Association International Conference in London on July 13, 2026. The study, which analyzed data from 214,251 participants across 14 countries and regions, was simultaneously published in The Lancet Healthy Longevity.

The research was led by scientists at the University of Southern California and drew on harmonized survey data collected between 2009 and 2023 from 11 long-running studies of aging. It examined 12 modifiable risk factors for dementia previously identified by the Lancet Commission. The participating countries and regions included the United States, England, Ireland, Northern Ireland, four regions of Europe, Korea, Mexico, China, Malaysia, Brazil, and India.

Nichols, a research scientist with the Center for Economic and Social Research at the USC Schaeffer Institute for Public Policy & Government Service, highlighted stark regional differences in specific risk factors. Low education was a prevalent dementia risk factor for 85.6% of people in China compared with 12.0% of Americans. Conversely, obesity affected 44.9% of older adults in the U.S., but only 13.3% of people in India. In the U.S., the five most prevalent dementia risk factors were hypertension, smoking, high LDL cholesterol, obesity, and physical inactivity.

Despite these differences, the study also revealed consistent patterns across countries. Cardiovascular risks—such as high cholesterol and hypertension—tended to cluster together, as did risky behaviors like smoking and drinking. Poor hearing, poor vision, and low education frequently co-occurred in the study population. More than 50% of individuals in the study had at least two dementia risk factors, and in 11 of the 14 countries and regions, more than 20% of participants had at least four risk factors.

"To create policies and programs that can help lower the burden of dementia, we need to understand where dementia risk factors are most common and how they differ across countries," Nichols said. She added, "This study offers the most detailed international data to date on how dementia risk factors vary from place to place."

Nichols emphasized that the findings show both important differences and shared patterns. "I was less surprised by the differences and more surprised by some of the similarities, particularly in the ways these risks are patterned across settings," she said. "That has real implications for how we design prevention strategies and interventions, because some things are more consistent across places than we might expect."

She also stressed the potential for individual and societal action. "Risk for these late-life outcomes isn't predetermined," Nichols said. "These are risk factors you experience over the life course, and you can have an impact on changing your own risk—while also recognizing the ways broader societal factors shape that risk, too."

The Alzheimer’s Association International Conference, where the findings were presented, drew 10,200 attendees from 115 countries, an increase of 1,700 from the previous year. Alzheimer’s disease is a neurodegenerative condition and the most common form of dementia, accounting for approximately 60–70% of cases.

Why It Matters

The study provides the most comprehensive cross-national comparison of dementia risk factors to date, offering data that could inform targeted public health strategies. With more than half of participants exhibiting multiple modifiable risks, the findings underscore the potential for prevention through both individual behavior change and policy interventions addressing structural conditions like education and healthcare access.

By identifying which risk factors are most prevalent in specific regions—and which patterns hold universally—the research helps governments and health systems prioritize interventions. As global dementia cases rise, such evidence-based approaches may be critical to reducing future disease burden.