Air pollution may be linked to childhood anxiety, study says

Exposure to traffic-related air pollution (TRAP) and childhood anxiety may be correlated, according to a new study by researchers at the University of Cincinnati in Ohio, which published this week in the journal Environmental Research.

Researchers examined the correlation between exposure to TRAP and childhood anxiety by looking at the altered neurochemistry in pre-adolescents. They evaluated imaging of 145 children at an average age of 12 years old, looking specifically at the levels of myo-inositol found in the brain through a specialized MRI technique, magnetic resonance spectroscopy. Myo-inositol is a naturally-occurring metabolite mainly found in specialized brain cells known as glial cells, that assists with maintaining cell volume and fluid balance in the brain, and serves as a regulator for hormones and insulin in the body. Increases in myo-inositol levels correlate with an increased population of glial cells, which often occurs in states of inflammation, researchers said in a statement.

The researchers found that, among those exposed to higher levels of recent TRAP, there were significant increases of myo-inositol in the brain, compared to those with lower TRAP exposure. They also observed increases in myo-inositol to be associated with more generalized anxiety symptoms. In the higher, recent exposure group, the team saw a 12 percent increase in anxiety symptoms, according to the study abstract.

Exposure to air pollution is a well-established global health problem associated with complications for people with asthma and respiratory disease, as well as heart conditions and an increased risk of stroke, and is responsible for millions of deaths annually, according to the World Health Organization. Emerging evidence now suggests that air pollution may also impact the metabolic and neurological development of children.

This is the first study to use neuroimaging to evaluate TRAP exposure, metabolite dysregulation in the brain and generalized anxiety symptoms among otherwise healthy children, researchers said. However, they also noted that the observed increase in reported generalized anxiety symptoms in this cohort of typically developing children was relatively small and are not likely to result in a clinical diagnosis of an anxiety disorder.