A major study led by the University of Southern California found that the most common controllable risk factors for dementia, such as low education, high blood pressure, and smoking, vary significantly from country to country. The findings were presented on July 12 at the Alzheimer's Association International Conference 2026 in London and published in The Lancet Healthy Longevity.
The research involved more than 214,000 older adults across 14 countries and regions. According to 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, "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. 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 team combined harmonized survey data from long-running aging studies conducted between 2009 and 2023 in locations including the United States, England, Ireland, Northern Ireland, four regions of Europe, Korea, Mexico, China, Malaysia, Brazil, and India. Jinkook Lee of USC is principal investigator of both this project and India's Longitudinal Aging Study.
Researchers analyzed twelve modifiable risk factors identified by the Lancet Commission on dementia—such as hearing loss, depression, physical inactivity, and social isolation—examining their prevalence as well as how they varied by age group, gender, or education level. They also studied how often multiple risk factors appeared together in individuals.
The researchers said their findings could help guide decision-makers in developing dementia-prevention strategies tailored to specific populations. For example: "a program that connects people to care for diabetes could be redesigned to address the entire cluster of related cardiometabolic risks," such as high cholesterol or hypertension.
Nichols said that while broader societal influences matter too, "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." Future work may include newer potential risk factors like poor sleep or expand coverage to additional countries such as Kenya or Egypt as new data becomes available.
