Global Study of 214,000 Older Adults Reveals Striking Country-Specific Patterns in Dementia Risk Factors
Key Insights
A USC-led study of more than 214,000 older adults across 14 countries finds that modifiable dementia (search) risk factors such as low education, high BMI, and hypertension (search) vary dramatically by country, challenging one-size-fits-all prevention approaches.
Low education affected 85.6% of older adults in China versus only 12.0% in the United States, while high BMI was present in 44.9% of Americans compared to just 13.3% of Indians.
Despite country-level differences, cardiovascular risks like high cholesterol and hypertension (search) clustered together globally, as did behavioral risks such as smoking and drinking, offering opportunities for bundled interventions.
A sweeping international analysis of more than 214,000 older adults across 14 countries and regions has revealed that the most common modifiable risk factors for dementia (search) differ dramatically from one nation to another, challenging the assumption that prevention strategies developed in wealthy Western countries can be applied uniformly around the world.
The study, led by researchers at the USC Schaeffer Institute (search) for Public Policy & Government Service in collaboration with Brown University and Johns Hopkins University (search), was presented at the Alzheimer's Association International Conference (AAIC) 2026 in London and published in The Lancet Healthy Longevity.
"Most of what scientists know about preventing dementia (search) comes from research in wealthy countries such as the United States and those in Western Europe," said lead author Emma Nichols, a research scientist with the Center for Economic and Social Research at the USC Schaeffer Institute (search). The research team set out to determine whether those findings hold true in low- and middle-income countries.
Stark Contrasts Across Borders
The differences were striking. Low education affected 85.6% of older adults in China but only 12.0% of those in the United States. High BMI, a measure of excess body weight, was found in 44.9% of Americans compared with just 13.3% of people in India. These disparities underscore the need for country-specific prevention frameworks rather than global, one-size-fits-all recommendations.
The research team used harmonized survey data collected between 2009 and 2023 through the Gateway to Global Aging Data project, combining information from long-running aging studies in the United States, England, Ireland, Northern Ireland, four regions of Europe, Korea, Mexico, China, Malaysia, Brazil, and India. Jinkook Lee of the Center for Economic and Social Research at the USC Schaeffer Institute (search) serves as principal investigator of the Gateway to Global Aging Data project as well as the Longitudinal Aging Study in India.
Unexpected Similarities in Risk Clustering
Even though individual risk factors differed from country to country, many of them appeared together in similar combinations worldwide. Cardiovascular conditions such as high cholesterol and hypertension (search) frequently clustered together, while behaviors like smoking and drinking also tended to occur as groups.
"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," Nichols 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."
The researchers examined 12 modifiable dementia (search) risk factors identified by the Lancet Commission on dementia, including hearing loss, depression (search), physical inactivity, and social isolation. They measured how common each risk factor was, how it differed by age, gender, and education level, and how often multiple risk factors occurred together in the same individual.
Implications for Tailored Prevention Programs
According to the researchers, the findings could help governments and health organizations create prevention programs that better match the needs of their own populations. For example, a program that helps people manage diabetes (search) could also be expanded to address related cardiometabolic risks such as high cholesterol and hypertension (search), allowing multiple connected health issues to be tackled together.
Nichols emphasized that the results also carry an encouraging message for individuals. "Risk for these late-life outcomes isn't predetermined. 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."
Future studies will likely examine additional modifiable risk factors, including poor sleep, while expanding the research to more countries as comparable datasets become available. Data collection is already underway in additional countries, including Kenya and Egypt.
The study was supported by the National Institutes of Health under grant R01AG030153. Additional authors include senior author Jinkook Lee, Michael Markot, Drystan Phillips, and Jenny Wilkens of the Gateway to Global Aging Data team; co-first author Zachary Kunicki of the Warren Alpert Medical School of Brown University; and Alden Gross of the Johns Hopkins Bloomberg School of Public Health.