A new study, published in BMJ Open-Access this week, found a significant link between the level of air pollution in a community and the mental health of the children living there. After controlling for socio-economic status and other potential variables, researchers in Sweden discovered a strong association between the concentration of air pollution in a neighborhood and the amount of ‘antipsychotic’ and psychiatric drugs prescribed to children. The link remained strong even at pollution levels well below half of what is considered acceptable by the World Health Organization (WHO).
In 2013 the World Health Organization named air pollution “the world’s largest single environmental health risk,” responsible for an estimated 7 million deaths per year. Since then, however, new research has also begun to fill in the picture on the mental health effects of air pollution.
A number of studies have observed a correlation between mental health outcomes, like depression and anxiety, and the presence of environmental pollutants including air pollution. For example, a study published last year identified an association between exposure to air pollution, namely fine particulate matter, and heightened anxiety symptoms in over 70-thousand women. Another study conducted by the VA last year found evidence suggesting that air pollution was associated with increased stress levels.
Epidemiological studies, taking wider public health approaches, have also addressed this issue, connecting air pollution to cognitive decline in both children and adults. Earlier this year, researchers at the Columbia Center for Children’s Environmental Health found that prenatal exposure to common emissions from motor vehicles, power generation, smoking, and coal may influence the development of children, leading to poor social skills and difficulty managing emotions and impulses. While this type of research shows strong correlations, it is unable to prove a definitive causal link. Some scientists have gone further, however, and explored biological mechanisms through which different forms of air pollution may directly impact mental health.
In 2008, a major study published in the journal Toxicology proposed a mechanism of action for such an effect. The researchers studied children and young adults who were otherwise healthy but died suddenly. They found that those who had lived in cities with high levels of air pollution had inflammation in their nervous systems and an altered immune system response. They concluded that air pollution should be considered a risk factor for neurodegenerative conditions like Alzheimer’s and Parkinson’s.
Some have suggested that these studies can be explained by the fact that socially marginalized groups are often forced to live in neighborhoods with the greatest risks for environmental pollutants and that social and economic status have an impact on the incidence of mental health issues. Like previous studies, researchers here have attempted to control for indicators of social and economic status.
In this latest longitudinal study, exposure to air pollution was assessed over time nationally across Sweden and compared to data on psychiatric medications dispensed to children and adolescents under 18. This data was then run through nationwide registries on social and economic indicators to control for potential confounders.
They found that relatively small increases in the amount of air pollution in a given community were correlated with significant increases in the percentage of children being prescribed drugs for a mental health issue.
While the WHO and EU currently suggest that air pollution be kept under an annual level of 40 µg/m3, the researchers found a disproportionate level of psychiatric prescriptions occurring at pollution levels as low as 15 µg/m3 of NO2. Even levels as low as 10 µg/m3 were linked with as much as a 9% increase in the prescription of psychiatric drugs to minors.
“If confirmed,” the researchers conclude, “our findings implicate that there may be a link between exposure to air pollution and dispensed medications for certain psychiatric disorders in children and adolescents.”
The study has been published Open-Access and can be read in full here →
Oudin, A., Bråbäck, L., Åström, D.O., Strömgren, M. and Forsberg, B., 2016. Association between neighbourhood air pollution concentrations and dispensed medication for psychiatric disorders in a large longitudinal cohort of Swedish children and adolescents. BMJ open, 6(6), p.e010004. (Full Text)