Air pollution exposure may increase risk for depression, suicide
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Higher levels of air pollution exposure may be associated with increased rates of depression and death by suicide among those exposed, according to results of a systematic review and meta-analysis published in Environmental Health Perspectives.
“There is already good evidence of a range of harmful health impacts of air pollution exposure, such as heart and lung diseases, with increasing evidence for other outcomes, such as pregnancy complications and dementia, so there is already a clear need for policies and public health measures to reduce levels of outdoor air pollution in our cities,” Isobel Braithwaite, MPH, MBBS, of the department of psychiatry at University College London, told Healio Psychiatry. “Our review adds to the weight of evidence for the benefits of cleaner air, since air pollution may not only worsen physical but also mental health. It also suggests that the population groups which may be particularly vulnerable to harmful effects of air pollution include not only children and people with physical health conditions, but potentially also people with mental health conditions.”
According to Braithwaite and colleagues, mounting research is uncovering a link between exposure to fine particulate matter (PM2.5) air pollution and “tenable mechanisms” that may affect the risk for multiple mental health outcomes. To test this association, the researchers investigated quantitative associations between PM and multiple adverse mental health outcomes, including anxiety, bipolar disorder, depression, psychosis and suicide.
They identified a total of 1,826 citations and included 22 that matched their inclusion criteria for PM exposure. Meta-analysis of associations between PM2.5 exposure for more than 6 months and depression revealed a pooled OR of 1.102 per 10 µg/m3 PM2.5 increase (95% CI, 1.023-1.189) for a 10% increase. The researchers found a statistically significant association between short-term PM10 exposure and suicide in meta-analysis as well as statistically significant associations between long-term PM2.5 exposure and anxiety in two of the included studies. They noted that reducing global average exposure to PM2.5 air pollution from 44 µg/m3 to 25 µg/m3 may result in a 15% reduction in depression risk worldwide.
“We were somewhat surprised at the results of the meta-analyses we conducted and that they seem to be of a similar size to some physical health impacts of particulate matter, as the evidence base is still fairly small and these aren't health outcomes that people would often think of in relation to air pollution,” Braithwaite said. “But given the mounting evidence of negative effects of air pollution on dementia risk and the development of the brain, we did think that the associations found from pooling the studies' results were biologically plausible.” – by Joe Gramigna
Disclosures: The authors report no relevant financial disclosures.