An international team led by researchers from the University of Chicago (IL, USA) and Aarhaus University (Denmark) have performed a large dataset analysis study to determine whether air quality has an effect on the development of psychiatric and neurological disorders.
The results of the study, published in PLOS Biology, suggest that exposure to environmental pollution may increase the prevalence of conditions such as bipolar disorder and schizophrenia.
Data from both Danish and American populations were included in the study.
First, air pollution exposure in different regions was determined utilizing data from the US Environmental Protection Agency and a Danish national pollution register.
Using computational modelling, regional differences in air pollution levels were then compared with incidence rates of psychiatric and neurological disorders. A US health insurance database including 11 years of claims from over 150 million individuals and a Danish national treatment register containing 23 years of health information on 1.4 million Danes were analyzed.
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“Our study shows that living in polluted areas, especially early on in life, is predictive of mental disorders in both the United States and Denmark,” commented first author Atif Khan (University of Chicago).
The authors of the paper suggest that a possible explanation for this correlation is that pollution induces neuroinflammation in the brain.
“We hypothesized that pollutants might affect our brains through neuroinflammatory pathways that have also been shown to cause depression-like signs in animal studies,” explained Andrey Rzhetsky (University of Chicago), lead author of the research.
However, the results of the study have been considered controversial. “This study on psychiatric disorders is counterintuitive and generated considerable resistance from reviewers,” stated Rzhetsky.
A reviewer involved in the editorial processing of the paper, John Ioannidis (Stanford University, CA, USA) commented, “Despite analyses involving large datasets, the available evidence has substantial shortcomings and a long series of potential biases may invalidate the observed associations.”
Both the authors of the paper and Ioannidis recommend that further investigation is required for us to fully understand the links between environmental pollution and neurological disorders.
Sources: Khan A, Plana-Ripoll O, Antonsen S et al. Environmental pollution is associated with increased risk of psychiatric disorders in the US and Denmark. PLoS Biol. 17(8), e3000353 (2019); PLOS. Is pollution linked to psychiatric disorders? Press release: www.plos.org/