Fine-particle air pollution can cause the damage to brain structures over long-term exposure, according to the researchers at Beth Israel Deaconess Medical Center and the Boston University School of Medicine.
The study analyzed 900 participants of the Framingham Heart Study in the greater Boston area, and used satellite imagery to assess prolonged exposure to ambient fine particulate matter, equivalent to a 2.5 millionth of a meter.
Such particles come from power plants, factories, truck, cars and burning wood, the researchers said.
During the years 1995 through 2005, the scientists used MRIs to determine how the pollution had affected the patients. They found the group had a 0.32 percent smaller total cerebral brain volume and a 46 percent higher risk of covert brain infarcts, a kind of undetected stroke, they found.
"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," said Elissa Wilker, the lead author of the study, and a researcher at Beth Israel and at the Harvard T.H. Chan School of Public Health.
"We found that people who live in areas where there are higher levels of air pollution had smaller total cerebral brain volume and were more likely to have evidence of covert brain infarcts," she added.
Other studies have shown a connection between air pollution and strokes, as well. A team from the University of Edinburgh found that particulate and gaseous air pollution led to worse outcomes for stroke, in a study they published last month in the British Medical Journal.
The U.S. Environmental Protection Agency currently provides an air-quality measure updated regularly showing particulate measures across the nation.
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HUMAN STUDIESNEUROSCIENCEENVIRONMENTALHEALTHEXCLUSIVE