Exposure to environmental pollution may cause brain changes that make people more vulnerable to developing autism or schizophrenia, according to a new study published in Environmental Heath Perspectives.
This research falls in line with a 2013 study published in JAMA Psychiatry, which demonstrated an epidemiological link between pollution and autism; the researchers found that children who lived in areas with high levels of traffic pollution seemed to be more likely to be diagnosed with the neurodevelopmental disorder.
Now, researchers from the University of Rochester have uncovered the biological mechanism that may explain how pollution can put people at a higher risk for both autism and schizophrenia.
“From a toxicological point of view, most of the focus of air pollution research has been on the cardiopulmonary system – the heart and lungs,” study author Deborah Cory-Slechta, professor of environmental medicine at the University of Rochester, told FoxNews.com. “But I think it’s becoming increasingly clear that the adverse things happening there are also happening in the brain, and this may be adding to risks for neurodevelopmental disorders like autism that we hadn’t thought about before.”
Cory-Slechta and her colleagues executed several experiments to examine the effects of air pollution on different groups of young mice during a critical time in the brain’s development. Each group of mice was exposed to levels of air pollution equivalent to those seen in rush hour traffic.
After four hours of pollution exposure during two four-day periods, mice exposed to pollution experienced marked changes in behavior compared to mice living in an environment with filtered air.
“We see changes in learning produced by these exposures in males and females, and in levels of activity, and we saw deficits in memory in both males and females,” Cory-Slechta said. “We also had a measure of attention, looking at impulsive-like behaviors, which we only tested in males, and there too we saw the effects of postnatal exposure.”
These effects were lasting, with researchers reporting behavioral differences between the two groups of mice even 10 months after the initial pollution exposure.
The team also examined the brains of the mice exposed to pollution, and discovered rampant inflammation and enlargement of the ventricles – the chambers on either side of the brain containing cerebrospinal fluid.
In humans, enlarged ventricles are symptomatic of a brain condition called ventriculomegaly, which is accompanied by varying degrees of neurodevelopmental impairment. Furthermore, ventriculomegaly is often associated with damage to the corpus callosum – the white matter tracts sitting above the ventricles – which connect the two sides of the brain.
“[The corpus callosum] are important for processing cognitive kinds of behaviors, social behaviors and emotional behaviors,” Cory-Slechta said. “And autism is thought to be a disease in which that kind of connectivity is lost, and you also see ventricular enlargement in autism and schizophrenia as well.”
These brain changes were seen predominantly in male mice after pollution exposure, which is significant because men are more likely to be diagnosed with both autism and schizophrenia than women.
While most research on pollution focuses on large-particle pollution – the only type monitored by the U.S. Environmental Protection Agency – this research focused on the effects of exposure to lesser-known superfine particles.
“That kind of air pollution produces inflammation, it is going to produce inflammation peripherally and in the brain as well. And when you produce inflammation in the brain, you can kill cells there,” Cory-Slechta said.
Overall, Cory-Slechta hopes that more research into the connection between autism and pollution exposure may lead to a better understanding of the damaging effects of superfine pollution particles. Furthermore, it could offer clues as to why some people may be more susceptible to developing autism than others.
“I think in particular autism has been very difficult to discover the ideology of, so to speak, we know there are genetic underpinnings but they don’t fully account for [everything], and the leads in terms of, ‘Are there environmental exposures?’ have been relatively few,” Cory-Schleta said. “And it might be interesting if it turns out air pollution can contribute.”