According to the World Health Organization (WHO), as of 2021, about 57 million people around the world were living with dementia, with more than 60% of cases occurring in low- and middle-income countries.
The latest research has identified 14 potentially modifiable risk factors for dementia.
Now, a new study published in the journal The Lancet Healthy Longevity has found differences in risk factors around the world, as well as similarities, with certain risk factors clustering in similar patterns.
For this study, researchers evaluated survey data collected between 2009 and 2023 from more than 214,000 older adults.
Participants were located in 14 different countries, including Mexico, Korea, China, Malaysia, Brazil, India, the U.S., the U.K., and Ireland.
Researchers analyzed information on 12 known modifiable risk factors for dementia, including:
Emma Nichols, PhD, an epidemiologist and research scientist for the Center for Economic and Social Research at the Schaeffer Institute for Public Policy and Government Service at the University of Southern California (USC), and lead author of this study, told Medical News Today that it’s important for researchers to continue to collect more information on known modifiable dementia risk factors because without data on risk factors, it’s impossible to study and understand their impacts on health.
“This knowledge can help us understand the causes of dementia and can inform the design of interventions and policies to reduce the burden of disease,” Nichols explained.
“Investigating how these risk factors vary across settings and how they are patterned across populations provides valuable evidence to inform policy and interventions in different contexts,” she said.
At the study’s conclusion, researchers found marked differences in dementia risk factors across countries.
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For example, scientists discovered that low education affected 85.6% of older adults in China, but only 12% in the U.S., and when looking at obesity and high body mass index (BMI), this dementia risk factor affected about 44.9% of Americans, compared to only 13.3% of people living in India.
“Differences in the prevalence of risk factors across contexts suggest that different approaches are likely needed to best address dementia burden in these different settings,” Nichols said. “For example, addressing low education would be likely to have an important and meaningful impact in China, but impacts would not be as large in the United States.”
Additionally, researchers noted that certain dementia risk factors tended to cluster in similar patterns worldwide. This included cardiovascular risk with risk factors including hypertension and high cholesterol, or risky behaviors such as smoking and excessive alcohol consumption.
“Similarities in the patterning of risk factors across studies suggest that despite observed differences, interventions and policies across contexts could use similar designs to account for risk factor clustering patterns,” Nichols said.
MNT spoke with Dung Trinh, MD, an internist with MemorialCare Medical Group and chief medical officer of the Healthy Brain Clinic in Irvine, CA, who was not involved in this study, about the findings.
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Trinh said these findings reinforce something already seen clinically: dementia risk is rarely driven by a single issue, and the most important risks can look very different from one patient or community to another.
“I was especially struck by how often risk factors clustered together across countries — for example, hypertension with high cholesterol or smoking with alcohol use — because that supports a more integrated approach in primary care rather than addressing each risk factor in isolation,” Trinh continued. “At the same time, the wide differences in prevalence remind us not to assume that a prevention strategy developed in one population will automatically fit another.”
MNT also spoke with Raphael Wald, PsyD, a board-certified neuropsychologist at Marcus Neuroscience Institute, a part of Baptist Health, who was likewise not involved in this study.
Wald said this study’s findings also show that a dementia diagnosis is not entirely predetermined.
“There are risk factors across a person’s life that may influence brain health later on, including blood pressure, cholesterol, diabetes, physical activity, smoking, depression, hearing loss, vision loss, social isolation, and education level,” he explained.
“For patients, I think the hopeful message is that brain health can be supported over time. We cannot eliminate every risk, and not every case of dementia is preventable, but many of the same steps that protect the heart and overall health may also protect the brain.”
— Raphael Wald, PsyD
As this study examined how modifiable dementia risk factors differ between countries and regions, including low- and middle-income countries, Trinh said this is important information for doctors in high-income countries like the U.S. to be aware of.
“Immigrants may arrive with different lifetime exposures, educational opportunities, health-care access, cultural norms, and levels of awareness or treatment of conditions such as hypertension, diabetes, hearing loss, or depression,” he explained.
“Country-level findings should never be used to stereotype an individual patient, but they can help clinicians ask better questions and avoid assuming that U.S.-based risk patterns apply equally to everyone,” he said.
“The practical lesson is to combine culturally informed care with individualized screening, including attention to possible under-diagnosis of cardiometabolic and sensory conditions.”
— Dung Trinh, MD
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Wald said he would like to see healthcare organizations use this type of information to move away from a one-size-fits-all approach and toward prevention strategies that reflect the communities they actually serve.
“For example, if a health system serves a population with high rates of hypertension, diabetes, and obesity, dementia-prevention efforts should be integrated into cardiovascular and primary care programs,” he detailed.
“A patient coming in for blood pressure or diabetes management should also hear that controlling those conditions may support long-term brain health. If another community has high rates of hearing loss, vision loss, or social isolation, then screening, referrals, and community support programs may be especially important,” he added.
“This study is a reminder that dementia prevention needs to be personalized. In the U.S., that means doctors should consider not only a patient’s current health status, but also the social, cultural, and medical history that shaped their risk over a lifetime.”
— Raphael Wald, PsyD
