NEW DELHI: An analysis of more than two lakh people across 14 countries found that common, controllable dementia risk factors, such as low education and obesity, can vary widely between high-income and low- and middle-income countries, with over 50 per cent of individuals across regions having at least two risk factors.
Broadly similar clusters of risk factors -- related to cardiovascular diseases, risky behaviours, and social or sensory factors -- were observed across settings, according to findings published in The Lancet Healthy Longevity journal.
Researchers, led by those at the University of Southern California, Brown University and Johns Hopkins University in the US, combined survey data from long-running aging studies in 14 places, including England, China, Brazil and India, collected between 2009 and 2023.
Data from the Longitudinal Aging Study in India was included.
Twelve modifiable risk factors identified by the Lancet Commission on dementia, such as hearing loss, depression, physical inactivity and social isolation were analysed, comparing how common each factor was, how it varied by age, gender and education level, and how often multiple risk factors showed up together in the same person.
"We observed some variation in the prevalence and patterns (by age, gender, and education) of risk factors between HICs (high income countries) and LMICs (low and middle income countries)," the authors wrote.
"Risk factors commonly co-occurred across settings, with more than 50 per cent of individuals having at least two risk factors across all countries and regions," they said.
Low education was found to affect 85.6 per cent of older adults in China but only 12 per cent in the US, while a high BMI (body mass index) affected 44.9 per cent of Americans, compared to 13.3 per cent of people in India.
The researchers also found that cardiovascular risks such as high cholesterol and hypertension or risky behaviours of smoking and drinking tended to cluster together in similar patterns worldwide.
The similarities in risk factors, particularly in the ways these risks are patterned across settings, have "real implications for how we design prevention strategies and interventions, because some things are more consistent across places than we might expect," lead author Emma Nichols, a research scientist at the University of Southern California's Schaeffer Institute for Public Policy and Government Service, said.
Nichols added that the consistency of these clusters was the most unexpected part of the findings.
The findings can help guide decision-makers and health organisations in designing dementia-prevention strategies tailored to their own populations, the researchers said.
For example, a programme that connects people to care for diabetes could be redesigned to address the entire cluster of related cardiometabolic risks, such as high cholesterol and hypertension, at the same time, they said.
For the average person, Nichols said, the takeaway is that dementia risk is not fixed or fated.
"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 -- while also recognising the ways broader societal factors shape that risk, too," Nichols said.