Air Pollution Exposure May Raise Brain Damage Risk

Long-term exposure to air pollution may damage brain structures and impair cognitive function in middle-aged and older adults.

In a study published in the May 2015 issue of Stroke, researchers evaluated more than 900 participants aged 60 years and older who were free of dementia and stroke. They considered the participants’ prolonged exposure to ambient fine particulate matter with a diameter of at least 2.5 millionth of a meter (PM2.5), as well as their total cerebral brain volume, hippocampal volume, white matter hyperintensity volume, and covert brain infarcts.

After completing their analysis, the researchers determined a PM2.5 increase of only 2 µg/m³ was associated with an increased risk of covert brain infarcts and smaller cerebral brain volume, which is equivalent to approximately 1 year of brain aging.

“These results are an important step in helping us learn what is going on in the brain,” said study co-author Elissa Wilker, ScD, a researcher in the Cardiovascular Epidemiology Research Unit at Beth Israel Deaconess Medical Center, in a press release. “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.”

Senior investigator Sudha Seshadri, MD, a professor of neurology at Boston University School of Medicine, noted participants living in more polluted areas had not only the brain volume of an individual aged 1 year older than those living in less polluted areas, but also a 46% higher risk of silent strokes.

“This is concerning since we know that silent strokes increase the risk of overt strokes and of developing dementia, walking problems, and depression,” Dr. Seshadri said.

The research teams plans to expand on their findings by investigating the impact of air pollution over a longer time period and its effect on brain shrinkage and other risks, according to Dr. Seshdri.