The quality of the air we breathe may be a trigger for so-called psychiatric problems, and the age we start breathing polluted air could also be a factor.
Bipolar disorder, major depression and schizophrenia may all be caused by poor air quality—and the chances of schizophrenia, in particular, double if we're exposed to polluted air during our first 10 years.
Although genetics and life experiences may play a part in psychiatric problems, environmental factors could be the third element of a complex interplay, say researchers from the University of Chicago, who explored the effects of air pollution in the US and Denmark.
They used Environmental Protection Agency (EPA) measures to assess air quality in the US and a national pollution register in Denmark, and then set those against two big population data sets, including 151 million US residents and 1.4 million people in Denmark—and, for the Danish data, they were also able to assess exposure to air pollution in a person's first 10 years.
They found a direct link between air quality and a risk of psychiatric disorders. "Living in polluted areas, especially early on in life, is predictive of mental disorders," said researcher Atif Khan.
They suspect that pollution is causing inflammation in the brain, and this is triggering the disorders—as earlier animal studies had predicted. In those studies, researchers discovered that small particulate matter, or fine dust, was travelling to the brain after being breathed in. Animals exposed to high levels of pollution showed signs of cognitive impairment and depression-like behavior.