Living amid pollution increases risk of major mental illness or depression, study suggests

Living in an area with high air pollution increases the chance of suffering from a major mental illness or depression, scientists have discovered.

In the biggest study ever looking into a link between emissions and neuropsychiatric disorders, researchers compared 151 million health insurance records with pollution statistics across the US.

The team from the University of Chicago then verified their findings using data from health registers covering 1.4 million people in Denmark.

Americans living in the most highly polluted areas were at 27 percent increased of being diagnosed with  bipolar disorder while incidents of major depression rose by six per cent.

Likewise Danes who were exposed to high emissions before the age of 10 were 50 per cent more likely to suffer major depression in adulthood, and at more than double the risk of schizophrenia and personality disorders, compared to people who grew up in the freshest air.

British scientists said the results suggested that improving air quality might offer a ‘rare’ primary healthcare opportunity to prevent mental illness.

Study author Dr Atik Khan, a computational biologist, said: “Our studies in the United States and Denmark show that living in polluted areas, especially early in life, is predictive of mental disorders.

“These neurological and psychiatric diseases - so costly in both financial and social terms - appear linked to the physical environment, particularly air quality.”

In recent years, scientists have attempted to uncover the genetic variations which make some people more susceptible to mental health problems.

But they have increasingly found that DNA seems to account for just 10 per cent of the risk for most people, leading experts to think that a complex interplay of genetics, neurochemicals and social factors is to blame.

Recent studies on rodents have shown that small particulates, such as those emitted by diesel engines, can travel to the brain through the nose and lungs, and animals exposed to pollution have shown signs of cognitive impairment and depression-like symptoms.

“We hypothesised that pollutants might affect our brains through neuroinflammatory pathways that have also been shown to cause depression-like signs in animal studies," said Dr Andrey Rzhetsky, who led the new study.

Air pollution has already been implicated in lung disease, diabetes and heart attacks and in 2016 researchers at Lancaster University found that magnetic particles produced by car engines and brakes in the brains of people suffering from Alzheimer’s disease.

British scientists said that people who live in more polluted areas tended to be less healthy as a result of social class which could account for some of the increased risk, but said cutting emissions could help to lower the rate of mental illness in the UK.

Dr Ioannis Bakolis, Lecturer in Biostatistics and Epidemiology, at King’s College London: “These findings add to the current evidence from previous studies of a possible link between air pollution and psychiatric disorders.

“Improving air quality is a tractable, though complex, issue and therefore measures to reduce air pollution may represent a potentially impactful and rare primary health measure for the prevention of psychiatric disorders, although we still need to learn much more about if and how this would work.”

Dr Daniel Maughan, Associate Registrar for Sustainability at the Royal College of Psychiatrists, added: “While the study does not show that air pollution causes mental illness, it does suggest that a strong link exists between early exposure to air pollution and an increased risk of developing several different mental illness including schizophrenia, bipolar, depression and personality disorder.

“However, there are many environmental factors which could contribute to poor mental health for those people living in areas of high pollution – such as population density and diminished access to green spaces – so it is therefore difficult to isolate poor air quality as the cause of mental illness.”

The research was published in the journal PLOS Biology.