Physical, social factors may be ageing your brain faster than you think

Pollution, heat and inequality may significantly accelerate brain ageing, with a global study showing combined exposures can raise risk sharply and impact long-term cognitive health

Your surroundings may be making your brain age faster, according to a new global study. Researchers from the Global Brain Health Institute (GBHI) at Trinity College Dublin have found that a mix of everyday physical and social exposures, from air pollution to inequality, could raise the risk of accelerated brain ageing.

 

The researchers in the study titled The exposome of brain aging across 34 countries, published in Nature Medicine, say that when these physical and social exposures combine, they could raise the risk of faster brain ageing by up to nine times.

What does the study reveal about environmental and social drivers of brain ageing?

The study introduces the concept of the “exposome”, which is the totality of environmental exposures an individual experiences over their lifetime, and how it impacts brain health.

 

 

Researchers analysed data across 34 countries and found that environmental and social conditions are not just background factors; they play a central role in how quickly the brain ages.

 

Importantly, the study highlights that these exposures do not act in isolation. Instead, they interact in complex ways, amplifying the overall risk of faster cognitive decline and structural brain changes.

 

The analysis identified the following key physical exposures:

• Air pollution
• Extreme temperatures (both heat and cold)
• Limited access to green spaces

These factors were strongly linked to structural brain ageing, meaning actual physical changes in the brain. Regions affected include those responsible for memory, emotional regulation, and involuntary bodily functions such as heart rate and breathing.

 

The researchers suggest that these changes may be driven by biological processes like neuroinflammation, oxidative stress, and vascular dysfunction, all of which are known to damage brain tissue over time.

 

Beyond physical exposures, the study also examined social determinants such as:

• Socioeconomic inequality
• Living conditions
• Access to resources

These social factors were found to independently, and in combination, affect brain ageing. When layered with environmental risks, they can significantly amplify the overall impact.

 

The researchers found the combined effect of physical and social exposures could increase the risk of accelerated brain ageing by up to nine times.

 

The researchers identified distinct brain markers linked to different types of exposures:

• Physical exposures (like pollution) were mainly associated with structural changes, which are actual alterations in brain anatomy.
• Social exposures appeared to influence broader functional outcomes, potentially affecting cognition, behaviour, and mental resilience.

Together, these findings suggest that brain ageing is not a single process but a combination of structural and functional changes shaped by our environment.

Why is this study important amid climate change and urbanisation trends?

With rapid urbanisation, climate change, and widening inequalities, many of these risk factors are becoming more widespread.

 

This study shifts the conversation from individual lifestyle choices alone to a broader, systemic view of brain health. It suggests that improving environmental conditions such as cleaner air, more green spaces, and reduced inequality could be as crucial as diet and exercise in protecting cognitive function.

How can you reduce your risk of accelerated brain ageing?

While large-scale environmental change requires policy action, individuals can still take steps to mitigate risk:

• Spend more time in green spaces where possible
• Reduce exposure to pollution (e.g., using masks in high-smog areas)
• Maintain cardiovascular health through diet and exercise
• Build social connections and reduce stress

However, the study makes it clear that individual efforts alone are not enough, system-level interventions are essential to address the root causes.