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Environmental pollution tied to increased risk for psychiatric disorders

Study findings published in PLOS Biology indicated that air pollution was significantly linked to increased risk for psychiatric disorders in the United States and Denmark.

“Concern has been growing about the diverse negative health effects of air pollution, raising the possibility that air quality may play an important role in mental health and cognitive function,” Atif Khan, PhD, from University of Chicago’s Institute of Genomics and Systems Biology, and colleagues wrote.

In their exploratory analyses, Khan and colleagues examined data from two independent, large datasets — 151 million individuals from a U.S. insurance claims dataset and 1.4 million individuals from a Danish national treatment registers — to determine the connection between environmental pollution and risk for neuropsychiatric disorders.

For the U.S. data, researchers measured individuals’ exposures to pollutants at a county level and for the Denmark data, they estimated environmental factors as exposure to air pollution during initial 10 years of life. Disorders included in analyses were bipolar disorder, major depression, personality disorder, schizophrenia, epilepsy and Parkinson’s disease.

Using the U.S. data, the results showed that air quality was the strongest predictor for bipolar disorder diagnosis, with the worst air quality linked to a 27% increase (95% CI, 15-40) in the apparent rate of bipolar disorder. In addition, the estimated rate of bipolar disorder was 16.4% (95% CI, 5.8-29.6) higher in the most densely populated counties.

 

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Khan and colleagues reported a 6% increase in the diagnosis rate of major depressive disorder (95% CI, 0-12.4) in regions with the worst air quality; however they also reported positive associations between population density, urbanicity and the rate of MDD diagnosis. Furthermore, they found an association between land pollution and increased risk for personality disorder, with the regions with worst land quality linked to an estimated 19.2% increase (95% CI, 8.8-29.9) in the prevalence of personality disorder.

However, the researchers found pleasant weather days had a protective effect across all neuropsychiatric disorders included, especially for bipolar disorder. They estimated that counties with the highest number of pleasant weather days were tied to a 21.8% (95% CI, 16.8-26.8) decreased rate of bipolar disorder.

Using the Danish data, Khan and colleagues also found that compared with individuals with the least exposure, those who lived in areas with the highest exposure to air pollution were at 50% increased risk for MDD, 148% increased risk for schizophrenia and 162% increased risk for personality disorders.

"Our studies in the United States and Denmark show that living in polluted areas, especially early in life, is predictive of mental disorders," Khan said in a press release. "These neurological and psychiatric diseases — so costly in both financial and social terms — appear linked to the physical environment, particularly air quality." – by Savannah Demko

Disclosure: The authors report no relevant financial disclosures.