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Dementia prevention has long been guided by research from the wealthiest nations which tend to cluster together risk factors, but a sweeping new study suggests that approach may not translate everywhere.
“Prevention was never one size fits all,” John La Puma, physician and author of Indoor Epidemic, told Newsweek.
His comments come as researchers led by the University of Southern California report that the most common controllable risk factors for dementia differ sharply from country to country, meaning that prevention strategies built for one nation may fall flat in another.
What The Study Found
The research, led by USC alongside colleagues at Brown University and Johns Hopkins University, analyzed data from more than 214,000 older adults across 14 countries and regions, including the U.S., England, Ireland, Northern Ireland, four European regions, Korea, Mexico, China, Malaysia, Brazil and India. The data, gathered between 2009 and 2023, came from long-running aging studies compiled by the Gateway to Global Aging Data team.
Researchers examined 12 modifiable dementia risk factors identified by the Lancet Commission, including hearing loss, depression, physical inactivity and social isolation. They compared how common each factor was across countries, how the factors varied by age, gender and education, and how often several risk factors appeared together in the same person.
The findings were published in The Lancet Healthy Longevity.
Sharp Differences Between Countries
The gaps between countries were substantial. Low education affected 85.6 percent of older adults in China but just 12 percent in the U.S. High BMI, a measure of excess body weight, affected 44.9 percent of Americans but only 13.3 percent of people in India.
“85.6 percent of Chinese seniors are at risk because of low education, and 44.9 percent of Americans are at risk because of high BMI,” La Puma added, noting one factor left out from the work. “The study measured 12 risk factors, but they left out daylight exposure, which has been shown to reduce risk 16 to 17 percent with the right dose.
“It’s the one thing that would improve the biology in all 14 countries studied.”
Unexpected Similarities
Despite those differences, the study found that certain risk factors consistently grouped together in similar ways across countries. Cardiovascular risks, such as high cholesterol and hypertension, tended to appear together, as did behavioral risks like smoking and drinking.
Lead author Emma Nichols, a research scientist at the USC Schaeffer Institute for Public Policy & Government Service’s Center for Economic and Social Research, said this consistency was the most unexpected result.
“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 in a statement. “That has real implications for how we design prevention strategies and interventions, because some things are more consistent across places than we might expect.”
What It Means For Prevention
The researchers say the results could help governments and health organizations build dementia-prevention programs tailored to their own populations rather than importing strategies designed elsewhere, which could lead to greater prevention efforts overall. For instance, a program built to manage diabetes could be expanded to address an entire cluster of related cardiometabolic risks, such as cholesterol and blood pressure, at once.
Reference
Nichols, E. et al. (2026). Differences in the prevalence and patterns of dementia risk factors across 14 countries and regions: a harmonised cross-national analysis. The Lancet Healthy Longevity. http://dx.doi.org/10.1016/j.lanhl.2026.100867
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