Common levels of traffic pollution can hinder cognitive function within a matter of only hours, a new study by the University of Victoria and the University of British Columbia has found.
The study, published earlier this month in the journal Environmental Health, provides the first evidence in humans – from a controlled experiment – of altered brain network connectivity directly linked to pollution.
It also found that just two hours of exposure to diesel exhaust causes a decrease in the brain’s functional connectivity, which reflects the ability of different areas of the brain to interact and communicate with one another.
“For many decades, scientists thought the brain may be protected from the harmful effects of air pollution,” Dr. Chris Carlsten, professor and head of respiratory medicine and the Canada Research Chair in occupational and environmental lung disease at UBC, said in a news release Tuesday (Jan. 24).
For the experiment, 25 healthy adults were briefly exposed to diesel exhaust and filtered air at different times in a laboratory setting. The brain activity of participants was additionally measured before and after each exposure using functional magnetic resonance imaging (fMRI).
Researchers analyzed changes in the brain’s default mode network (DMN), a set of inter-connected brain regions that play a significant role in memory and internal thought. The fMRIs revealed that participants had decreased functional connectivity in widespread regions of the DMN after exposure to diesel exhaust, compared to filtered air.
“We know that altered functional connectivity in the DMN has been associated with reduced cognitive performance and symptoms of depression, so it’s concerning to see traffic pollution interrupting these same networks,” Jodie Gawryluk, assistant professor of psychology at UVic, told Black Press Media. “But more studies are needed to look at the long-term effects, like what happens after we have repeated exposures for a long time – we might not be able to recover so easily from that.”
“Air pollution is now recognized as the largest environmental threat to human health and we are increasingly seeing the impacts across all major organ systems,” said Carlsten. “I expect we would see similar impacts on the brain from exposure to other air pollutants, like forest fire smoke. With the increasing incidence of neurocognitive disorders, it’s an important consideration for public health officials and policymakers.”
The study was conducted at UBC’s Air Pollution Exposure Laboratory at Vancouver General Hospital, which is equipped with a state-of-the-art exposure booth that is able to mimic what it’s like to breathe a range of different air pollutants.
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