We knew that air pollution is harmful to health and contributes to the development of diseases such as high blood pressure, dementia or Alzheimer’s, or even ADHD in children, but a new study has found that even brief exposure to polluted air traffic can have an impact on the brain and provides the first evidence that the connectivity of the brain network in humans can be altered by this cause.
The authors of the work are researchers from the University of British Columbia and the University of Victoria and have shown that usual levels of traffic pollution can affect our brain function in a matter of hours; Specifically, they verified that an exposure of only two hours to the gases emitted by diesel engines causes a reduction in the functional connectivity of the brain, which constitutes a measure of how the different regions of the brain interact and communicate with each other.
“For many decades, scientists thought that the brain could be protected from the harmful effects of air pollution,” said Dr. Chris Carlsten, professor and director of respiratory medicine and Canada’s research chair in occupational lung diseases and environmental studies at UBC and lead author of the research. “This study, which is the first of its kind in the world, provides new evidence supporting a connection between air pollution and cognition.” His findings have been published in Environmental Health.
How Diesel Engine Exhaust Affects the Human Brain
The study involved 25 healthy adults who were briefly exposed to diesel exhaust and filtered air at various times in a laboratory setting. Before and after each exposure, the researchers used functional magnetic resonance imaging (fMRI) to measure the brain activity of these people and analyzed changes in the brain’s default mode network (DMN), a set of interconnected brain areas involved in memory and internal thought. The fMRI results showed that participants’ functional connectivity was reduced over large areas of the DMN after exposure to diesel fumes, compared to filtered air.
“Air pollution is now recognized as the greatest environmental threat to human health”
“We know that impaired functional connectivity in the DMN has been associated with reduced cognitive performance and symptoms of depression, so it is concerning to see traffic pollution disrupting these very networks,” said Dr. Jodie Gawryluk, Professor of psychology at the University of Victoria and first author of the study, who adds that although further research is needed, it is possible that these changes “may affect people’s thinking or ability to work.”
The changes detected in the brain of the participants were temporary and after exposure the connectivity returned to normal, but Dr. Carlsten believes that if the exposure is continued the effects could be maintained, so he has recommended that people take into account how is the air they breathe to take the necessary measures to limit their exposure to harmful substances such as the gases emitted by cars.
The new study focused solely on the effects of traffic pollution on cognition, but Carlsten cautions against the potential dangers of other combustion products. “Air pollution is now recognized as the greatest environmental threat to human health and we are increasingly seeing impacts on all major organ systems,” he says, adding that “similar impacts on the brain from exposure to other air pollutants, such as smoke from forest fires.” This scientist considers that taking into account the increase in the incidence of neurocognitive disorders, it is essential that those responsible for public health adopt preventive measures.
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