Where you live could shape your dementia risk, massive study finds
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- USC researchers analyzed data from 214,000+ older adults across 14 countries and regions, finding that the 12 modifiable dementia risk factors identified by the Lancet Commission differ dramatically between nations.
- Low education affected 85.6% of older adults in China but only 12.0% of those in the United States, illustrating the scale of cross-country variation in a single risk factor.
- High BMI was found in 44.9% of Americans versus 13.3% of people in India, the study found, highlighting how the same risk factor plays out very differently by region.
- Despite national variation, cardiovascular conditions (high cholesterol, hypertension) and behavioral risks (smoking, drinking) clustered together in similar combinations worldwide, researcher Emma Nichols said.
- Lead author Emma Nichols said the cross-country similarities in risk patterning were the study's biggest surprise, reshaping how prevention strategies might be designed.
- The findings were presented at the Alzheimer's Association International Conference 2026 in London and published in The Lancet Healthy Longevity, using harmonized survey data from 2009–2023.
Why it matters: Most prior dementia research has centered on high-income Western countries, yet this study shows 85.6% of older Chinese adults carry low-education risk versus 12% of Americans — meaning prevention blueprints built on Western data will systematically miss the dominant modifiable risks in Asia, Latin America, and other regions now expanding aging studies.
