Living further away from major roadways has been linked to better brain health by new research.
Long-term exposure to even moderate levels of air pollution, the study found, is bad for the brain.
Air pollution may cause poor cognitive function and ‘silent strokes’, which have been linked to dementia.
The study also found that people exposed to more air pollution had smaller brains.
Dr Elissa Wilker, an epidemiologist at Beth Israel Deaconess Medical Center who led the study, said:
“This is one of the first studies to look at the relationship between ambient air pollution and brain structure.
Our findings suggest that air pollution is associated with insidious effects on structural brain aging, even in dementia- and stroke-free individuals.”
The study looked at how far people lived from the nearest roadway.
It also used satellite imagery to work out their average exposure to fine particulate matter.
All the participants in the study were over 60 and free from dementia and stroke.
Professor Sudha Seshadri, a neurologist at Boston University School of Medicine and one of the study’s authors, explained the results:
“This study shows that for a 2 microgram per cubic meter of air (μg/m3) increase in PM2.5 [particular matter bigger than 2.5 millionths of a meter], a range commonly observed across major US cities, on average participants who lived in more polluted areas had the brain volume of someone a year older than participants who lived in less polluted areas.
They also had a 46 percent higher risk of silent strokes on MRI.
This is concerning since we know that silent strokes increase the risk of overt strokes and of developing dementia, walking problems and depression.
We now plan to look at more the impact of air pollution over a longer period, its effect on more sensitive MRI measures, on brain shrinkage over time, and other risks including of stroke and dementia.”
Particles of pollution can travel deep into the lungs and have been linked to strokes, heart attacks and other cardiovascular problems.
Dr Elissa Wilker said:
“These results are an important step in helping us learn what is going on in the brain.
The mechanisms through which air pollution may affect brain aging remain unclear, but systemic inflammation resulting from the deposit of fine particles in the lungs is likely important.”
The study was published in the journal Stroke (Wilker et al., 2015).
Tree brain image from Shutterstock