Exposure to air pollution may contribute to autism and schizophrenia, according to the findings of a US academic study.
A study by the University of Rochester Medical Center looked at the impacts of air pollution on mice, finding that exposure in early life produces harmful changes in their brains, including an enlargement of part of the brain that is seen in humans who have autism and schizophrenia.
As in autism and schizophrenia, the study found the changes occurred predominately in males. The mice also performed poorly in tests of short-term memory, learning ability, and impulsivity.
According to lead author of the study and professor of environmental medicine at the University, Deborah Cory-Slechta, the findings are consistent with several recent studies that have shown a link between air pollution and autism in children.
This includes a 2013 study in JAMA Psychiatry which reported that children who lived in areas with high levels of traffic-related air pollution during their first year of life were three times as likely to develop autism.
Dr Cory-Slechta said: “Our findings add to the growing body of evidence that air pollution may play a role in autism, as well as in other neurodevelopmental disorders.”
She said that in three sets of experiments, mice under two weeks’ old were exposed to levels of air pollution typically found in mid-sized U.S. cities during rush hour for four hours each day over two four-day periods.
In one group of mice, the brains were examined 24 hours after the final pollution exposure. In all of those mice, the study found inflammation was rampant throughout the brain, and the lateral ventricles – chambers on each side of the brain that contain cerebrospinal fluid – were enlarged two or three times their normal size.
Dr Cory-Slechta added: “When we looked closely at the ventricles, we could see that the white matter that normally surrounds them hadn’t fully developed. It appears that inflammation had damaged those brain cells and prevented that region of the brain from developing, and the ventricles simply expanded to fill the space.”
The problems were also observed in a second group of mice 40 days after exposure and in another group 270 days after exposure, indicating that the damage to the brain was permanent. Brains of mice in all three groups also had elevated levels of glutamate, a neurotransmitter, which is also seen in humans with autism and schizophrenia.
Dr Cory-Slechta said: “I think these findings are going to raise new questions about whether the current regulatory standards for air quality are sufficient to protect our children.”
Published in the journal Environmental Health Perspectives, the study was funded by two grants from the National Institute of Environmental Health Sciences.