How Traffic Is Rotting Your Brain

Being stuck in traffic typically inspires one of two impulses: Murderous road rage, or deep existential dread. Neither, though, is your fault. Nope, according to a new study in the journal Environmental Health, the culprit for the middle finger you just directed at the guy who cut you off is actually air pollution.

“For many decades, scientists thought the brain may be protected from the harmful effects of air pollution,” study co-author Chris Carlsten, the Canada Research Chair in occupational and environmental lung disease at University of British Columbia, said in a statement. “This study provides fresh evidence supporting a connection between air pollution and cognition.”

Carlsten and his colleagues exposed 25 healthy adults to either diesel exhaust or filtered air in a lab setting for two hours (prayers up to the diesel exhaust group), while their brains were monitored via functional magnetic resonance imaging, or an fMRI. The researchers found that individuals who breathed in more pollution experienced changes in the brain’s default mode network (DMN), a part of the brain linked with memory, introspection and mind wandering. In particular, the fMRI data indicated that there was a decrease in “functional connectivity” between parts of the DMN compared to those who inhaled 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,” first author of the study Jodie Gawryluk, a psychology professor at the University of Victoria, added. “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.”

Gawryluk and Carlsten both recommend taking the obvious precaution of rolling up the windows when in traffic. Still, as Carlstein explained, “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. 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.”

If there’s a silver lining to any of this, it’s that at least we now better understand why convertible drivers are the way they are.