Fine particle exposure linked to brain damage in older adults 

Source: Amanda Peterka, E&E reporter • Posted: Monday, April 27, 2015

A study of older adults has found that long-term exposure to air pollution is associated with brain damage and a type of “silent” stroke.

The study led by researchers from the Beth Israel Deaconess Medical Center and Boston University School of Medicine examined more than 900 people at least 60 years or older. They found that participants who were exposed to higher levels of fine particulate matter had brains that were more likely to show signs of aging and a type of silent stroke that results from blockages in the blood vessels supplying their brains.

The authors said the results were concerning. Silent strokes increase the risk of overt strokes, dementia and depression, among other negative health effects.

“This is one of the first studies to look at the relationship between ambient air pollution and brain structure,” Elissa Wilker, a researcher in the Cardiovascular Epidemiology Research Unit at Beth Israel Deaconess Medical Center, said in a statement. “Our findings suggest that air pollution is associated with insidious effects on structural brain aging, even in dementia- and stroke-free individuals.”

The study was first published online yesterday and will appear in the May print issue of the journal Stroke. It was funded by grants from the National Institutes of Health and U.S. EPA.

The study’s 900 participants, all of whom were free of dementia and stroke, lived in the New England region and were part of the Framingham Heart Study, a long-term project of the National Heart, Lung and Blood Institute that seeks to identify the causes of cardiovascular disease. They were examined as part of the heart study in the 1998-2001 time frame.

In the study, the authors analyzed exposures to fine particulate matter, or particles that are one-thirtieth the width of a human hair. They measured how far the participants lived from major roadways — cars and trucks are a major source of fine particles — and used satellite imagery to assess exposure.

According to the results, an increase of 2 micrograms per cubic meter of fine particle pollution was associated with smaller brain volume. The results meant that people living in more highly polluted areas had the brain volume of someone a year older.

On average, participants exposed to pollution levels commonly observed in major cities in the United States had a 46 percent higher risk of silent stroke than those living in less polluted areas.

“These results are an important step in helping us learn what is going on in the brain,” Wilker said. “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 researchers are planning further study on the impacts of air pollution on brain shrinkage, stroke and dementia.