Breathing dirty air in your 40s and 50s could take a toll on your brain well into your senior years.
The findings from a King’s College London study link higher midlife exposure to common pollutants, such as nitrogen dioxide and particulate matter, with slower processing speed, poorer cognitive test scores, and measurable changes in brain structure later in life.
What’s happening?
The research, published in The Lancet Healthy Longevity journal, followed more than 1,700 participants from the long-running National Survey of Health and Development over a 26-year period.
At multiple points between ages 43 and 69, participants’ verbal memory and processing speed were tested. At age 69, they also took the Addenbrooke’s Cognitive Examination III, a screening tool for cognitive impairment and dementia.
Results showed that individuals with higher exposure to nitrogen dioxide and particulate matter from age 45 onwards had lower ACE-III scores and slower thinking speeds, even after accounting for childhood cognitive ability and earlier-life pollution exposure.
In a subset of participants who underwent brain scans, high pollutant exposure was associated with smaller hippocampal volumes, linked to memory loss, and larger ventricular volumes, which typically increase as brain tissue shrinks.
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Why is this trend concerning?
These brain changes are hallmarks of cognitive decline and dementia, conditions projected to affect 153 million people globally by 2050.
While the impacts of pollution on heart and lung health are well documented, this study strengthens evidence that what we breathe may also influence how our brains age.
The fact that these effects were observed decades after the exposure period suggests that midlife air quality could shape neurological health later in life.
“Most of the world’s population is breathing toxic air above World Health Organization recommended limits, which could partly explain the increased dementia risk as people age,” said Professor Ioannis Bakolis, one of the study’s co-authors.
What’s being done about this dangerous situation?
Efforts to curb pollution, such as cleaner public transit, stricter emissions standards, and accelerating clean energy adoption, can help protect both brain and body health.
On a personal level, experts recommend reducing exposure during high-pollution days, supporting clean air policies, and encouraging urban green spaces that can help filter pollutants.
Policies like school districts switching to electric buses, entrance fees for cars during peak periods in NYC, and implementing clean air zones above major cities can all help reduce local pollution.
As the study’s lead author, Thomas Canning, noted, “reducing people’s exposure has the potential to help conserve cognition and brain structure as they age, even if this happens once they reach midlife.”
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