Study links pollution to autism, schizophrenia

ROCHESTER, N.Y. — Tiny bits of air pollution may irritate very young brains enough to cause problems, according to a study published in the journal Environmental Health Perspectives.

When mice younger than 2 weeks old were exposed to very small particles of pollutants, their brains showed damage that is consistent with brain changes in humans with autism and schizophrenia. That's not to say air pollution causes either one, said Deborah Cory-Slechta, professor of environmental medicine at the University of Rochester Medical Center and lead researcher in the study published Friday.

Research on mice doesn't always translate to humans. But Cory-Slechta said the results could lead to regulations on even the smallest types of pollutant particles.

"For me it's about primary prevention," she said. "Maybe we should be thinking about regulating differently. ...

"What it suggests is that maybe in terms of looking at levels of air pollution, maybe we should focus on monitoring of the ultrafine particles that are there," Cory-Slechta said.

Schizophrenia is a mental illness that interferes with a person's ability to think clearly, manage emotions, make decisions and relate to others, according to the National Alliance on Mental Illness.

Autism, and autism spectrum disorder, are terms for complex disorders in brain development, according to the advocacy group Autism Speaks. The disorders are present in varying degrees, and include difficulties in social situations, verbal and nonverbal communication, and repetitive behaviors.

The causes of both are a source of controversy and confusion. Cory-Slechta said that at one point, autism was thought to be a childhood form of schizophrenia.

"Like many complex disorders, it's not just one factor," she said. "If you think of it as a bucket and the rain drops are coming in, and the rain drops are risk factors for autism. Maybe some of the rain drops are genetic predisposition. Maybe the mother also had an infection during pregnancy and maybe the mother lives in a place where there are higher levels of air pollution."

In the analogy, the more rain in the bucket, the greater the risk, she said.

Decades of research has been done on air pollution and heart and lung disease. The effect on the brain is a newer field.

"To me, it's an argument that lower levels of air pollution has been a good thing," Cory-Slechta said. "For cardiovascular disease, that's well known. Now we're saying air pollution doesn't just affect the heart and lungs. It also seems to target the brain."

The University of Rochester Medical Center research built on other studies that have shown a link between air pollution and autism in children. Cory-Slechta noted a 2013 study in JAMA Psychiatry, formerly Archives of General Psychiatry, that reported children who lived with high levels of traffic-related air pollution during their first year were three times as likely to develop autism.

Sarah Milko is executive director of AutismUp, a Rochester-based education and support group for families.

"The cutting edge research being done at the University of Rochester Medical Center will hopefully start to bring us steps closer to getting answers to the autism epidemic," Executive Director Sarah Milko of AutismUp, a Rochester-based education and support group for families, wrote in e-mail.

The medical center's research took a new direction in trying to show whether ultrafine particles would damage the brain, and if so, how. The National Institute of Environmental Health Sciences, part of the National Institutes of Health, financed the three-year study.

Larger particles regulated by the Environmental Protection Agency actually are less harmful because the nose and lungs, working like strainers, keep them out of the bloodstream, Cory-Slechta said. But very fine particles, which aren't regulated, can slip through, travel through the lungs and be picked up in the bloodstream.

The researchers exposed mice for specific periods of time to levels of air pollution found during rush hour in cities such as Los Angeles, Boston, Atlanta and New York City. One group of mice was examined 24 hours after its final exposure, another group 40 days later and a third group 270 days later. There was evidence of permanent inflammation and high level of a neurotransmitter that is seen in humans with autism and schizophrenia.

But that doesn't mean a line — straight or squiggly — exists between pollution and brain disorders.

"I never use the word 'causes,'" Cory-Slechta said. "I try to make people understand it's the interaction of all these risk factors in your life, over your lifespan, that come together.

"There are things out there that are maybe protective of autism," she said. "It's the conglomeration, if you will. It's not just for autism or schizophrenia, but for a lot of other diseases and disorders."