A new global analysis of more than 214,000 older adults reveals that dementia risk factors vary widely by country, but some patterns are surprisingly consistent.
Why this matters
For decades, most research on dementia prevention has come from high-income countries like the U.S. and Western Europe. That left a big question: do those findings apply everywhere? A new study suggests the answer is no—and that has real implications for how we think about brain health as we age.
The study, led by researchers at the University of Southern California, looked at data from 14 countries and regions, including the U.S., England, China, India, and Brazil. It found that the prevalence of key dementia risk factors—like low education, high blood pressure, and smoking—varies dramatically from place to place. That means a one-size-fits-all approach to prevention is unlikely to work globally.
But the findings also carry a hopeful message: many of the biggest risk factors are modifiable. You can’t change your genes, but you can take steps to address things like high blood pressure, smoking, and physical inactivity. And understanding how these risks differ across populations can help public health officials target their efforts more effectively.
What the study found
The researchers analyzed harmonized survey data from more than 214,000 older adults, collected between 2009 and 2023. They examined 12 modifiable risk factors identified by the Lancet Commission on dementia, including hearing loss, depression, and social isolation.
The differences were striking. For example, low education affected 85.6% of older adults in China but only 12.0% in the U.S. High BMI—a measure of excess body weight—was found in 44.9% of Americans compared with just 13.3% of people in India.
Yet despite these differences, the study also found surprising similarities. Cardiovascular conditions like high cholesterol and hypertension often clustered together, and behaviors like smoking and drinking also tended to occur in groups. This suggests that certain combinations of risk factors are common across many countries, which could inform prevention strategies.
How to interpret the results
This is an observational study, so it can’t prove that these risk factors cause dementia. It only shows associations. The researchers also note that the data may not reflect current trends, since it was collected over a period ending in 2023.
Still, the study’s size and scope make it valuable. It’s one of the first to compare dementia risk factors across such a diverse set of countries, and it challenges the assumption that findings from high-income nations apply everywhere.
The authors emphasize that risk for late-life outcomes isn’t predetermined. As lead author Emma Nichols put it, ‘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.’
Practical next steps
For individuals, the takeaway is that many dementia risk factors are modifiable. That means you can take action to reduce your risk, regardless of where you live. Focus on things like controlling blood pressure, staying physically active, not smoking, and staying socially engaged.
For public health officials, the study suggests that prevention programs should be tailored to local populations. For example, in countries where low education is common, improving access to education could have a big impact. In places where high BMI is prevalent, weight management programs might be more effective.
The researchers plan to expand their work to more countries, including Kenya and Egypt, and to examine additional risk factors like poor sleep. As more data becomes available, we’ll get an even clearer picture of how to prevent dementia around the world.
Three things to remember
- Dementia risk factors vary widely by country, study finds.
- Low education affects 85.6% in China vs. 12% in U.S.
- High BMI found in 44.9% of Americans vs. 13.3% in India.
How to interpret it
Historical Biophysics & Lineage
The modern preprint’s finding that dementia risk factors vary by country directly validates the historical emphasis on modifiable vascular and lifestyle factors. Hachinski’s work established that cerebrovascular pathology contributes to dementia, and the current study confirms that hypertension—a key vascular risk factor—is a major contributor globally. Doll and Hill’s demonstration that smoking is a modifiable risk factor for chronic disease is extended here to dementia, with smoking prevalence varying by country. The study’s use of large-scale epidemiological data across diverse populations mirrors the Doll and Hill approach, reinforcing that these risk factors are not uniform but context-dependent, yet universally modifiable.
Ancestral parallel: Traditional lifestyles, such as those in rural India or China, often involve higher physical activity and diets low in processed foods, which may lower hypertension and smoking rates compared to Western populations. The physical mechanisms include improved endothelial function and reduced vascular inflammation from regular activity, and avoidance of tobacco’s neurotoxic effects. This aligns with the study’s finding that risk factor prevalence varies, suggesting that ancestral-like active lifestyles and plant-based diets could mitigate dementia risk by reducing vascular and metabolic stressors.
Source
This analysis is based on Where you live could shape your dementia risk, massive study finds from ScienceDaily Healthy Aging. Read the original report for full context.
Health note: This was an observational study, so it cannot prove cause and effect. The data may not reflect current trends, and the study only examined 12 risk factors.