Link between air pollution and anxiety in children investigated

Summary: Children exposed to higher levels of air pollution from traffic have increased levels of myo-inositol in the brain. The increase in myo-inositol was associated with higher risk of generalized anxiety in children.

Source: University of Cincinnati

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 according to the World Health Organization, is responsible for millions of deaths annually. Emerging evidence now suggests that air pollution may also impact the metabolic and neurological development of children.

A new study from researchers at the University of Cincinnati and Cincinnati Children’s Hospital Medical Center looks at the correlation between exposure to traffic-related air pollution (TRAP) and childhood anxiety, by looking at the altered neurochemistry in pre-adolescents.

“Recent evidence suggests the central nervous system is particularly vulnerable to air pollution, suggesting a role in the etiology of mental disorders, like anxiety or depression,” says Kelly Brunst, PhD, assistant professor in the Department of Environmental Health at the College of Medicine, and lead author on the study.

“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,” says Brunst.

The study was published by the journal Environmental Research and is available online.

The researchers evaluated imaging of 145 children at an average age of 12 years, 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.

They 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, we saw a 12% increase in anxiety symptoms,” says Brunst.

Brunst noted however, 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. “However, I think it can speak to a bigger impact on population health … that increased exposure to air pollution can trigger the brain’s inflammatory response, as evident by the increases we saw in myo-inositol,” says Brunst. “This may indicate that certain populations are at an increased risk for poorer anxiety outcomes.”

This shows traffic

They 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. The image is in the public domain.

Co-authors on the study include Patrick Ryan, PhD, associate professor; and Mekibib Altaye, PhD, research professor, both with dual appointments in the departments of pediatrics and environmental health at the College of Medicine, and with Cincinnati Children’s; Grace LeMasters, PhD, emeritus professor, Department of Environmental Health, UC College of Medicine; Kimberly Yolton, PhD, director of Research Section, General and Community Pediatrics at Cincinnati Children’s, and a professor of pediatrics in the College of Medicine; Kim Cecil, PhD, research professor of radiology, pediatrics and environmental health with UC and Cincinnati Children’s; and Thomas Maloney and Travis Beckwith, PhD, with the Department of Radiology at Cincinnati Children’s.

Funding: Funding for this project was provided by the National Institutes of Environmental Health Sciences (P30 ES006096, R00 ES024116, R01 ES019890, R01 ES11170, and R01 ES027224) and the National Center for Advancing Translational Sciences (NCATS, UL1 TR001425).

The authors cite no conflicts of interest.

About this neuroscience research article

Source:
University of Cincinnati
Media Contacts:
Alison Sampson – University of Cincinnati
Image Source:
The image is in the public domain.

Original Research: Closed access
“Myo-inositol mediates the effects of traffic-related air pollution on generalized anxiety symptoms at age 12 years”. Kelly J. Brunst, Patrick H. Ryan, Mekibib Altaye, Kimberly Yolton, Thomas Maloney, Travis Beckwith, Grace LeMasters, Kim M. Cecil.
Environmental Research. doi:10.1016/j.envres.2019.05.009

Abstract

Myo-inositol mediates the effects of traffic-related air pollution on generalized anxiety symptoms at age 12 years

Background
Exposure to traffic-related air pollution (TRAP) has been linked to childhood anxiety symptoms. Neuroimaging in patients with anxiety disorders indicate altered neurochemistry.

Objectives
Evaluate the impact of TRAP on brain metabolism and its relation to childhood anxiety symptoms in the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS).

Methods
Adolescents (n = 145) underwent magnetic resonance spectroscopy. Brain metabolites, including myo-inositol, N-acetylaspartate, creatine, choline, glutamate, glutamate plus glutamine, and glutathione were measured in the anterior cingulate cortex. Anxiety symptoms were assessed using the Spence Children’s Anxiety Scale. TRAP exposure in early-life, averaged over childhood, and during the 12 months prior to imaging was estimated using a validated land use regression model. Associations between TRAP exposure, brain metabolism, and anxiety symptoms were estimated using linear regression and a bootstrapping approach for testing mediation by brain metabolite levels.

Results

Recent exposure to high levels of TRAP was associated with significant increases in myo-inositol (β = 0.26; 95%CI 0.01, 0.51) compared to low TRAP exposure. Recent elevated TRAP exposure (β = 4.71; 95% CI 0.95, 8.45) and increased myo-inositol levels (β = 2.98; 95% CI 0.43, 5.52) were also significantly associated with increased generalized anxiety symptoms with 12% of the total effect between TRAP and generalized anxiety symptoms being mediated by myo-inositol levels.

Conclusions
This is the first study of children to utilize neuroimaging to link TRAP exposure, metabolite dysregulation in the brain, and generalized anxiety symptoms among otherwise healthy children. TRAP may elicit atypical excitatory neurotransmission and glial inflammatory responses leading to increased metabolite levels and subsequent anxiety symptoms.

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