A large USC-led study of more than 214,000 older adults in 14 countries and territories found that the most commonly controllable risk factors for dementia, such as low education, high blood pressure and smoking, vary widely from country to country, and that a one-size-fits-all approach to prevention will not work everywhere.
The findings, presented today at the Alzheimer’s Disease Society International Conference 2026 in London, are also published in the same journal. Lancet Health and Longevity. AAIC is the world’s largest forum for the dementia research community.
Most of what scientists know about preventing dementia comes from research in wealthy countries such as the United States and Western Europe. But the study, led by USC researchers and researchers from Brown University and Johns Hopkins University, aimed to see whether the same pattern holds true in low- and middle-income countries.
The differences were striking, but so were the similarities.
- Differences: Low educational attainment affected 85.6% of older adults in China compared to only 12.0% in the US, while high BMI (a measure of excess weight) affected 44.9% of Americans compared to 13.3% in India.
- Similarities: Certain risk factors, such as cardiovascular risk (such as high cholesterol and high blood pressure) and risky behaviors (such as smoking and drinking), tend to cluster in similar patterns around the world.
The consistency of these clusters was the most unexpected part of the findings, said lead author Emma Nichols, a research fellow at the Center for Economic and Social Research at the Schaefer Institute for Public Policy and Government Services at the University of Southern California.
“I wasn’t really surprised by the differences, but I was even more surprised by some of the similarities, particularly how these risks are patterned across environments,” Nichols said. “This has major implications for how we design prevention strategies and interventions, because some things are more consistent across locations than we would expect.”
For this study, researchers from the Gateway to Global Aging Data team combined harmonized survey data from longitudinal aging studies collected between 2009 and 2023 in 14 locations, including the United States, United Kingdom, Ireland, Northern Ireland, four regions of Europe, South Korea, Mexico, China, Malaysia, Brazil, and India. (Jin-kook Lee of the USC Schaefer Institute for Economic and Social Research is the Principal Investigator of the Global Gateway to Elderly Data Project and Principal Investigator of the Global Gateway to Elderly Data Project) Long-term aging research in India. )
They analyzed 12 modifiable risk factors identified by the Lancet Commission on Dementia (including hearing loss, depression, physical inactivity and social isolation) and compared the frequency of each factor. How do they differ by age, gender, and level of education? and the frequency with which multiple risk factors appear simultaneously in the same person.
Researchers say their findings should guide decision-makers and health organizations in developing tailored dementia prevention strategies for their populations. For example, programs that connect people to diabetes care could be redesigned to simultaneously address an entire cluster of associated cardiometabolic risks, such as high cholesterol and hypertension.
Nichols added that it’s important to note that for the average person, the risk of dementia is not fixed or fateful. “The risk of these late-life outcomes is not predetermined. These are risk factors that we experience throughout our lives, and we can influence to change our own risk, while also being aware of the ways in which wider social factors shape that risk.”
Future studies may also be expanded to include newer risk factors such as sleep deprivation and additional countries as more harmonized data become available. New data collection is already underway in other countries, including Kenya and Egypt.
About research
In addition to Nichols, other authors include senior authors Jin-Kook Lee, Michael Murcott, Drystan Phillips and Jenny Wilkens. Both are members of the Gateway to Global Aging Data team at the University of Southern California’s Schaefer Institute for Economic and Social Research. co-lead author Zachary Kunicki of Brown University Warren Alpert School of Medicine; Alden Gross of the Johns Hopkins Bloomberg School of Public Health.
This research was supported by the National Institutes of Health (grant R01AG030153).
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University of Southern California
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DOI: 10.1016/j.lanhl.2026.100867
