A sweeping international investigation, spearheaded by researchers at the University of Southern California (USC) and encompassing over 214,000 senior participants across 14 distinct nations and territories, has unearthed compelling evidence suggesting that strategies for dementia prevention must be finely tuned to local contexts. The study’s groundbreaking findings underscore the profound variability in the prevalence of key modifiable risk factors for dementia, such as educational attainment, blood pressure management, and smoking habits, across different global regions. This intricate mosaic of risk factors indicates that a uniform, one-size-fits-all approach to combating dementia on a worldwide scale is unlikely to yield consistent or optimal outcomes.
Presented at the prestigious Alzheimer’s Association International Conference 2026 in London, and concurrently published in the esteemed journal The Lancet Healthy Longevity, this research addresses a critical gap in our understanding of dementia. The Alzheimer’s Association International Conference (AAIC) stands as the foremost global gathering dedicated to advancing scientific knowledge in the field of dementia. Historically, the bulk of research concerning dementia prevention has been concentrated in high-income nations, including the United States and various Western European countries. To ascertain whether these established findings hold true universally, a collaborative effort involving researchers from USC, Brown University, and Johns Hopkins University was undertaken to meticulously examine data from both affluent and lower-to-middle-income countries.
The comprehensive analysis revealed a striking landscape of both pronounced disparities and, perhaps more surprisingly, a degree of unexpected commonality in the patterns of dementia risk. For instance, the study observed a substantial difference in the prevalence of low educational attainment, affecting a significant 85.6% of older adults in China, in stark contrast to only 12.0% in the United States. Conversely, the metric of Body Mass Index (BMI), an indicator of excess body weight, presented a different pattern, with 44.9% of American participants exhibiting a high BMI compared to a considerably lower 13.3% among individuals in India.
Despite these country-specific variations in individual risk factors, the research team identified a noteworthy trend: many of these risk factors tended to co-occur in predictable constellations across diverse populations. For example, cardiovascular health concerns, such as elevated cholesterol levels and hypertension, frequently appeared in tandem, mirroring the tendency for lifestyle behaviors like smoking and alcohol consumption to cluster together within individuals.
Emma Nichols, a lead author on the study and a research scientist affiliated with the Center for Economic and Social Research at the USC Schaeffer Institute for Public Policy & Government Service, highlighted these shared risk factor patterns as one of the most significant and unanticipated revelations of the research. "While the differences between countries were anticipated, it was the degree of similarity, particularly in how these risks are patterned across different settings, that proved most surprising," Nichols commented. "This has profound implications for the design of prevention strategies and interventions, suggesting that certain underlying mechanisms of risk are more consistent globally than we might have initially supposed."
The robust dataset underpinning this investigation was meticulously compiled using harmonized survey data gathered between 2009 and 2023 through the comprehensive Gateway to Global Aging Data project. This expansive dataset integrates information derived from long-standing aging studies conducted across 14 diverse geographical locations. These sites include the United States, England, Ireland, Northern Ireland, four distinct regions within Europe, South Korea, Mexico, China, Malaysia, Brazil, and India. Jinkook Lee, a key figure at the USC Schaeffer Institute’s Center for Economic and Social Research, serves as the principal investigator for both the Gateway to Global Aging Data project and the Longitudinal Aging Study in India, underscoring the extensive reach of his team’s data collection efforts.
The research team rigorously examined a predefined set of 12 modifiable dementia risk factors, as identified by the influential Lancet Commission on dementia. This comprehensive list included factors such as hearing impairment, depressive symptoms, physical inactivity, and social isolation. The study meticulously measured the prevalence of each risk factor, analyzed how its occurrence varied based on age, gender, and educational background, and quantified the frequency with which multiple risk factors co-existed within the same individual.
These meticulously gathered findings offer invaluable guidance for governments and public health organizations worldwide, empowering them to develop and implement dementia prevention programs that are more precisely tailored to the unique demographic and epidemiological profiles of their respective populations. For instance, a public health initiative designed to assist individuals in managing diabetes could be strategically expanded to simultaneously address related cardiometabolic risks, such as high cholesterol and hypertension. This integrated approach allows for the simultaneous management of multiple interconnected health issues, thereby maximizing efficiency and impact.
Nichols further emphasized that the study’s outcomes carry an empowering message for individuals regarding their personal health trajectories. "The risk for these late-life cognitive outcomes is not predetermined," she stated. "These are risk factors that accumulate over the course of a lifetime, and individuals possess the capacity to influence their own risk profile. It is also crucial, however, to acknowledge the pervasive influence of broader societal factors that shape these risks."
Looking ahead, future research endeavors are poised to delve into an even wider array of modifiable risk factors, including the impact of insufficient sleep, and to extend the scope of this vital inquiry to additional countries as comparable datasets become accessible. Data collection is already actively underway in emerging research sites, including Kenya and Egypt, promising further expansion of this critical global understanding.
The foundational work for this study was spearheaded by Emma Nichols of the USC Schaeffer Institute’s Center for Economic and Social Research. The research team also included esteemed contributors such as senior author Jinkook Lee, along with Michael Markot, Drystan Phillips, and Jenny Wilkens from the Gateway to Global Aging Data team. Co-first author Zachary Kunicki from the Warren Alpert Medical School of Brown University, and Alden Gross from the Johns Hopkins Bloomberg School of Public Health, were also instrumental in this collaborative endeavor. Funding for this significant research initiative was provided by the National Institutes of Health, specifically through grant R01AG030153.
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