Early Exposure to Air Pollution Associated with Schizophrenia, Autism

Supporting a previous study that associated air pollution with autism, researchers at the University of Rochester Medical Center (URMC) have discovered an additional link between early exposure to air pollution and schizophrenia.

For their study published in Environmental Health Perspectives, Deborah Cory-Slechta, PhD, and her colleagues exposed mice to air pollution levels similar to mid-sized US cities during rush hour. The mice were exposed to polluted air for 4 hours each day over the course of 2 4-day periods. The mice were subjected to the levels of air pollution at 4-7 and 10-13 postnatal days (PND), when brain development is crucial.

To understand the effect air pollution has on brain development, the researchers measured the mice’s “lateral ventricle area, glial activation, central nervous system (CNS) cytokines, and monoamine and amino acid neurotransmitters.”

In one group of mice, the investigators noted brain inflammation and lateral ventricles enlargement up to 2-3 times their normal size after as little as 24 hours of exposure. The same effects were noted in 2 other groups observed at 40 and 270 days, indicating permanent brain damage.

“Concentrated ambient ultrafine particles (CAPS)-exposed males have increased levels of major excitatory neurotransmitter glutamate in the hippocampus, a sign of excitotoxicity in that region,” the authors wrote. “CAPS-exposed females show a decrease in hippocampal gamma-aminobutyric acid (GABA), the major inhibitory neurotransmitter of the CNS.”

Additionally, the GABA modifications that occurred in the mice’s hippocampi — which are also seen in humans — were associated with schizophrenia and bipolar disorder diagnoses.

Another part of the study examined a form of ventricle dilation known as “ventriculomegaly, a neuropathology that has been associated with poor neurodevelopmental outcome, autism, and schizophrenia,” the authors noted. The enlargement was more pronounced in male mice, which human male autism and schizophrenia patients also experience, according to a statement provided by URMC.

The findings echoed a 2013 JAMA study that reported “exposure to traffic-related air pollution, nitrogen dioxide, PM2.5, and PM10 during pregnancy and during the first year of life was associated with autism.” In that study, researchers at the University of Southern California discovered children exposed to high amounts of air pollution were 3 times more likely to have autism than children exposed to normal levels.

As Cory-Slecta said the current study adds to the mounting evidence associating air pollution with autism, schizophrenia, and other neurodevelopmental disorders, she questioned whether “current regulatory standards for air quality are sufficient to protect our children.”

“Taken together, these data suggest that exposure to CAPS in the early postnatal period, at human- and environmentally-relevant levels, may represent a far greater public health concern than has previously been recognized as a risk factor contributing to intractable neurodevelopmental disorders such as autism and schizophrenia,” the authors concluded.