Wednesday, August 21, 2019

Polluted Air Harms Mental Health

We all know about the links between asthma and air pollution, now polluted air is being linked to mental illness. People who spend their childhood in areas with high levels of air pollution may be more likely to later develop mental disorders, research suggests.

Children growing up in the more polluted areas of London were more likely to have depression by the age of 18 than those growing up in areas with cleaner air.

Researchers in the US and Denmark has suggested a link between air pollution and an increased risk of mental health problems, including bipolar disorder, schizophrenia and personality disorders.

Insurance data for 151 million individuals collected between 2003 and 2013 was used to explore the rates of particular mental disorders in counties across the US. This was then analysed alongside the average level of air pollution in each county.
The team found the rate for bipolar disorder was 27% higher for counties in the bottom seventh for air quality compared with those in the top seventh (with the best air quality), once factors including age, sex, poverty levels in the county and average income were taken into account. A tentative link was also seen for depression and air pollution.
The team then looked at air pollution data from Denmark, which was collected on a scale of 1 sq km. 
They looked at air pollution exposure for the first 10 years in the life of 1.4 million individuals born and living in the country between 1979 and the end of 2002, as calculated from their home addresses. Levels of 14 pollutants were considered – compared with the 87 considered in the US part of the study – and used to provide a measure of overall air pollution exposure over those years. The team then explored subsequent diagnoses for bipolar disorder, schizophrenia, personality disorder and depression up to the end of 2016.
Once factors including age, sex and socioeconomic status were considered, the team found that the rate of all four mental disorders were higher among people who had greater exposure to overall air pollution during their childhood.
When participants were split into seven equal-sized groups, based on the air they were exposed to until the age of 10, the researchers found the bottom seventh (who experienced the worst air) had 29%, 148%, 51% and 162% higher rates for bipolar, schizophrenia, depression and personality disorder respectively than the top seventh (who had experienced the cleanest air).
The team suggested a number of explanations for how mental health is affected by air pollution, pointing to animal studies that had proposed one route could be that it triggered inflammation in the respiratory tract that then led to inflammation across the body, including the brain. Another suggestion was that air pollutants travelled from the nose to the brain where they accumulated, causing inflammation and damage.
If the links to mental health disorders are confirmed, they could – somewhat counterintuitively – offer some cause for hope. “Unlike genetic predisposition, environment is something we can change,” said Rzhetsky.
Dr Ioannis Bakolis, an expert in biostatistics from King’s College London, said the study added to previous evidence of a possible link between air pollution and mental health disorders.
“While causation cannot be proved, this work suggests substantial morbidity from mental disorders could be avoided with improved air quality,” he said.

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