Avoid walking or biking down busy streets: Traffic fumes may affect brain connectivity, new Canadian study shows

Exposure to diesel exhaust for two hours can cause a change in the brain’s functional connectivity, a new study from University of British Columbia and University of Victoria suggests. The altered functional connectivity returned to normal after exposure. “For many decades, scientists thought the brain may be protected from the harmful effects of air pollution,” said senior study author Dr. Chris Carlsten, professor and head of respiratory medicine and the Canada Research Chair in occupational and environmental lung disease at U.B.C. “This study, which is the first of its kind in the world, provides fresh evidence supporting a connection between air pollution and cognition.” Dr. Carlsten and colleagues recruited 25 healthy volunteers for the study. Each volunteer underwent four functional MRIs: before and immediately after being exposed to diesel exhaust for two hours, and before and after being exposed to filtered air for two hours. The volunteers were blinded to the exposure and there was a two-week-long delay between exposure to filtered air or diesel fumes. Volunteers cycled for 15 minutes on a stationary bike at the start of each hour or exposure to mimic physical activity. The researchers analyzed changes in the default mode network (DMN), a set of linked brain regions that play a role in memory and thought, as a measure of functional connectivity. There was no change in functional connectivity after people were exposed to diesel fumes, but a significant increase in functional connectivity after being exposed to filtered air. The authors suggest that the diesel fumes negated the positive effect of exercise on brain connectivity. Read: Promising gene therapy delivers treatment directly to brain “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,” said first author Jodie Gawryluk, associate professor of psychology at the University of Victoria in a press release. “While more research is needed to fully understand the functional impacts of these changes, it’s possible that they may impair people’s thinking or ability to work.” The study results are consistent with the findings of a German study published in Environmental Health Perspectives in 2022. It found exposure to air pollution and traffic noise led to more diffuse patterns of functional connectivity. “People may want to think twice the next time they’re stuck in traffic with the windows rolled down,” Dr. Carlsten said in a UBC press release. “It’s important to ensure that your car’s air filter is in good working order, and if you’re walking or biking down a busy street, consider diverting to a less busy route.” The study was conducted at UBC's air pollution exposure laboratory at Vancouver General Hospital. The paper was published in Environmental Health. Read: Climate Changed: Canada's health system isn't ready for new reality, say doctors

Avoid walking or biking down busy streets: Traffic fumes may affect brain connectivity, new Canadian study shows

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