Researchers analyzed 73 country-level environmental and social factors — from pollution and climate to inequality and political instability — in 18,701 participants across 34 countries. Using multimodal brain age clocks, they found that combined exposome burden accelerated brain aging 3.3 to 9.1 times more than clinical diagnoses like Alzheimer's disease. Physical exposures primarily damaged structural brain regions including limbic and subcortical areas, while social exposures disrupted functional networks in frontotemporal and limbic circuits. Aggregated exposome models explained up to 15.5 times more variance in brain aging than any single factor. Findings held across healthy individuals and those with neurodegenerative conditions, validated longitudinally across diverse global settings.
