Dementia Prevention Is Not One-Size-Fits-All, Study Shows

Modifiable dementia risk factors varied widely from country to country and a one-size-fits-all approach to dementia prevention will not work everywhere, data from 14 countries and regions showed.

Both differences and similarities emerged in a global analysis of risks for 214,000 older adults, reported Emma Nichols, PhD, of the University of Southern California in Los Angeles, at the Alzheimer’s Association International Conference.

Low education was a prevalent dementia risk factor for 85.6% of people in China compared with 12.0% of Americans, Nichols said. Obesity was a risk factor for 44.9% of older adults in the U.S., but only 13.3% of people in India.

Despite differences in prevalence, similar factors — like cardiovascular risks (high cholesterol, hypertension, and diabetes) or risky behaviors (smoking and drinking) — tended to cluster together. Poor hearing, poor vision, and low education also co-occurred frequently.

Risk factors often overlapped, with more than 50% of individuals having at least two risk factors, Nichols pointed out. In 11 countries and regions, the prevalence of at least four risk factors exceeded 20%.

The findings were published in Lancet Healthy Longevity.

“To create policies and programs that can help lower the burden of dementia, we need to understand where dementia risk factors are most common and how they differ across countries,” Nichols said.

“This study offers the most detailed international data to date on how dementia risk factors vary from place to place. The findings show both important differences and shared patterns across settings,” she told MedPage Today.

“This information can help governments, health systems, and communities design better prevention efforts focusing not only on individual risk factors, but also on the broader social and structural conditions that impact dementia risk,” Nichols added.

The findings have direct implications for dementia prevention, noted Michal Schnaider Beeri, PhD, of Rutgers University in New Brunswick, New Jersey, and Yian Gu, MD, MS, PhD, of Columbia University in New York City.

“The consistent emergence of cardiovascular, behavioral (smoking and excessive alcohol consumption), and sensory-social clusters provides empirical support for multidomain intervention models and suggests that prevention strategies tailored to these clusters might be both efficient and necessary,” Beeri and Gu wrote in a comment accompanying the study.

It’s not clear whether interventions structured around these empirically derived clusters would outperform the existing multidomain approaches used in the POINTER and FINGER trials, they observed.

“The cross-sectional design of the study also precludes assessment of how risk profiles evolve over time,” they added.

In 2024, the Lancet Commission identified 14 risk factors that were linked with dementia. Most evidence in the commission’s report came from high-income countries, creating a knowledge gap about risks in other places.

Using the Gateway to Global Aging platform, Nichols and colleagues combined harmonized survey data collected between 2009 and 2023 from 214,251 participants in 11 long-running studies of aging in 14 places — the U.S., England, Ireland, Northern Ireland, four regions of Europe, Korea, Mexico, China, Malaysia, Brazil, and India. U.S. data came from the Health and Retirement Study.

The researchers analyzed 12 of the Lancet Commission’s risk factors that were commonly available in the studies: low education, hearing loss, high LDL cholesterol, depression, physical inactivity, diabetes, smoking, hypertension, obesity, excessive alcohol use, social isolation, and vision loss. They evaluated the prevalence of each risk factor and patterns of occurrence.

Low education (particularly in low-income and middle-income countries), hypertension, and smoking were among the most prevalent risk factors in most areas. In the U.S., hypertension, smoking (former or current), high LDL cholesterol, obesity, and physical inactivity were the five most prevalent dementia risk factors.

The analysis was restricted to the risk factors reported in the Lancet Commission report and future updates should include additional variables as new evidence emerges, Nichols noted.

The researchers used binary versions of all risk factors to simplify interpretation comparisons. In some cases, continuous measures — pack-years of smoking, for example — can provide more detailed information.