A recent study published in Nature Medicine explores how our environment and life conditions shape how our brains age. The researchers looked at a concept called the “exposome,” which means the total set of environmental, social, and political factors a person experiences throughout life.
The study analyzed data from 18,701 people across 34 countries. Participants included both healthy individuals and people with brain-related conditions such as Alzheimer’s disease and mild cognitive impairment. The goal was to understand how different life exposures influence “brain age,” which is a way of measuring how old a brain appears compared to a person’s actual age.
One key finding was that looking at all exposures together gives a much clearer picture than studying them one by one. In fact, combined exposome factors explained up to 15 times more differences in brain aging than individual factors alone. This shows that our environment affects us in complex, overlapping ways rather than through single causes.
The researchers also discovered that different types of exposures affect the brain in different ways. Physical factors, such as pollution or climate conditions, were linked to faster aging in brain structure, especially in areas related to memory and movement. On the other hand, social factors (inequality, stress, and access to resources) were more strongly connected to changes in how the brain functions, particularly in networks involved in thinking and emotions.
Another important result was that people exposed to higher overall levels of environmental and social stress had a much greater risk of accelerated brain aging, up to nine times higher in some cases. Surprisingly, this effect was even stronger than the impact of having a diagnosed brain disease.
The study highlights that these exposures often work together in what scientists call a “syndemic,” meaning multiple problems interact and worsen each other. For example, living in a polluted area with high social inequality may have a combined effect that is worse than either factor alone.
In conclusion, this research shows that brain health is not only determined by biology or genetics, but also strongly shaped by the world we live in. It suggests that improving environmental conditions and reducing social inequalities could play a major role in helping people maintain healthier brains as they age.
Reference
- Legaz, A., Moguilner, S., Barttfeld, P. et al. The exposome of brain aging across 34 countries. Nat Med (2026). https://doi.org/10.1038/s41591-026-04302-z
Editor of Daily 27.
Predoctoral researcher at the Department of Sociology in University of Barcelona.