Where you live could shape your dementia risk, massive study finds
A huge global study found that preventing dementia may require different strategies in different countries, but many of the biggest risks can still be changed.
- Date:
- July 13, 2026
- Source:
- University of Southern California
- Summary:
- Researchers analyzing data from more than 214,000 people found that dementia risk factors differ widely across countries, challenging the idea of a one-size-fits-all prevention strategy. At the same time, they uncovered surprisingly consistent patterns that could help shape smarter, more targeted public health efforts.
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A new USC led study of more than 214,000 older adults from 14 countries and regions suggests that preventing dementia may require different strategies in different parts of the world. Researchers found that many of the most important modifiable dementia risk factors, including low education, high blood pressure, and smoking, vary dramatically between countries. The findings indicate that a single global approach to dementia prevention is unlikely to be effective everywhere.
The research was presented at the Alzheimer's Association International Conference 2026 in London and was also published in The Lancet Healthy Longevity. AAIC is the world's largest scientific meeting focused on dementia research.
Dementia Risk Factors Vary Around the World
Most existing research on dementia prevention has come from high income countries, including the United States and nations in Western Europe. To determine whether those findings apply more broadly, researchers from USC worked with colleagues at Brown University and Johns Hopkins University to examine data from both high income and low and middle income countries.
The results revealed major differences, along with some unexpected similarities.
For example, 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), on the other hand, was found in 44.9% of Americans compared with just 13.3% of people in India.
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 frequently clustered together, while behaviors like smoking and drinking also tended to occur as groups.
Lead author Emma Nichols, a research scientist with the Center for Economic and Social Research at the USC Schaeffer Institute for Public Policy & Government Service, said those shared patterns were among the study's biggest surprises.
"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."
Analyzing More Than 214,000 Older Adults
The research team used harmonized survey data collected between 2009 and 2023 through the Gateway to Global Aging Data project. The dataset combined information from long running aging studies in 14 locations, including 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 is principal investigator of the Gateway to Global Aging Data project as well as the Longitudinal Aging Study in India.)
Researchers examined 12 modifiable dementia risk factors identified by the Lancet Commission on dementia, including hearing loss, depression, 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.
Tailoring Dementia Prevention
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 could also be expanded to address related cardiometabolic risks such as high cholesterol and hypertension, 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.
About the Study
The study was led by Emma Nichols of the USC Schaeffer Institute's Center for Economic and Social Research. 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.
The research was supported by the National Institutes of Health (grant R01AG030153).
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Materials provided by University of Southern California. Note: Content may be edited for style and length.
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