According to a new study, long-term exposure to polluted air could cause indirect physical modifications in the brain that may lead to cognitive impairment and unnoticeable brain injury.
The study, which was conducted by the researchers from the Harvard School of Public Health, and published in the American Heart Association journal Stroke, states that long-term exposure to air pollution — even at low levels — can lead to brain damage that precedes other neurological disorders associated with old age.
Elissa H. Wilker, Sc.D., associate researcher at the Harvard School of Public Health, and the lead author of the study, said, “Long-term exposure to air pollution showed harmful effects on the brain in this study, even at low levels, particularly with older people and even those who are relatively healthy.”
For their study, the researchers tested the effects of long-term exposure to PM2.5, or fine particles found in the air like dust, dirt, soot, smoke, and liquid that measure less than 2.5 micrometers in diameter. Between 1995 and 2005, they used magnetic resonance imaging (MRI) to analyze the brain health of more than 900 healthy adults over the age of 60 living around Boston and New York.
They found that a PM2.5 increase of 2 micrograms per cubic meter of air, which is a common level in metropolitan regions, was linked to a 0.32% reduction in total brain volume and a 46% increased risk of covert brain infarcts, a type of so-called silent stroke. This often presents no outward symptoms but increases the risk of future strokes. These covert brain infarcts occur deep within the brain and are linked to poor cognitive function and dementia.
“It is the first study to examine a link between air pollution, brain volume and the risk of silent strokes in a population of older adults. We now plan to look at the impact of air pollution over a longer period, its effects on more MRI sensitive measures, on brain shrinkage over time and other risks including of stroke and dementia,” added Wilker.