Environmental Factors Found to Significantly Affect Biological Age of Brain: Study

A major international study led by the Global Brain Health Institute and Trinity College Dublin, published in Nature Medicine, reveals that brain aging is not shaped by a single factor—but by a complex interaction of environmental, social, and political conditions.

Analyzing data from 18,701 individuals across 34 countries, researchers explored the concept of the exposome—the total set of environmental and social influences a person experiences throughout life. They found that these factors act together in a “syndemic” way, meaning multiple exposures interact and amplify each other’s effects on brain health.

The study assessed 73 variables, including air pollution, climate conditions, green space availability, water quality, socioeconomic inequality, and political stability. When combined, these factors explained up to 15 times more variation in brain aging than any single factor alone.

Different types of exposures affected the brain in distinct ways. Physical factors such as pollution, extreme temperatures, and lack of green spaces were linked to structural brain aging, particularly in regions responsible for memory and emotional regulation. These changes are associated with biological processes like neuroinflammation, oxidative stress, and vascular damage.

In contrast, social factors—such as poverty, inequality, and limited social support—were strongly associated with accelerated aging in brain networks involved in thinking, emotional control, and social behavior. Chronic stress from these conditions may drive long-term adaptations that negatively impact brain function. Notably, these social influences sometimes had a greater effect than conditions like dementia.

The findings carry significant public health implications. While individual habits like diet and exercise remain important, they address only part of the risk. Broader interventions—such as reducing pollution, improving urban design, expanding green spaces, and strengthening social systems—could play a critical role in promoting healthy brain aging.

REFERENCE: Legaz, A., et al. (2026). The exposome of brain aging across 34 countries. Nature Medicine. DOI: 10.1038/s41591-026-04302-z. https://www.nature.com/articles/s41591-026-04302-z