Air pollution is linked to neuropsychiatric disorders such as bipolar disorders, major depression, personality disorders, and schizophrenia.
While the exact mechanism of action is not known, researchers suspect that air pollutants cause inflammatory and cell–damaging (cytotoxic) effects on brain’s nerve cells.
Researchers at the University of Chicago, USA and the University of Aarhus, Denmark found air pollution was associated with increased rates of bipolar disorders, major depression, personality disorders, and schizophrenia.
Air pollution and brain studies
Studies of effects of air pollution on brain have been done mainly on animals.
Such studies have shown that when exposed to air pollution, they demonstrate signs of cognitive impairment and depression–like symptoms.
More and more studies done on animals are showing that environmental pollutants cause damage to brain. They lead to inflammation and cellular damage to brain’s neural tissues. This leads to many psychiatric disorders.
Environmental factors and neuropsychiatric disorders studies
Factors studying the effect of environment on neuropsychiatric conditions have focused on home and family social environments. They have looked at childhood adversity, trauma, and before–birth (prenatal) influences.
But, very few studies have tried to find association between physical environments and mental illnesses.
In a paper published in Aug 2019 in the journal PLoS Biology, the researchers showed that living in polluted areas, particularly in the first ten years of life, is predictive of mental disorders.
The USA data
The researchers looked at a USA health insurance database of 151 million individuals. They looked at air quality, water, land environment and weather conditions. They also studied neuropsychiatric disorders in these individuals; viz., bipolar disorder, major depression, personality disorders, schizophrenia, epilepsy, and Parkinson’s disease.
The US Environmental Protection Agency (EPA) maintains records of 87 potential air pollutants over each county in the USA. There are nearly 3200 counties in the USA, with an average of 100,000 people living in each.
The researchers found that counties with the worst air quality had a 27% increase in bipolar disorder and 6% increase in major depression when compared to counties with the best air quality. Also, regions with the worst land quality were associated with an 19.2% increased risk in personality disorder.
The Denmark data
In Denmark, the enviromental pollution data is maintained over much smaller areas, often over each square kilometer area.
The researcher took the data from Danish national treatment registers. They found records of 1.4 million people who were born in Denmark between 1979 and 2002.
The scientists also studied the rates of neuropsychiatric conditions in Danish adults, who had lived in areas with poor environmental quality up to their tenth birthdays. They could do that in Denmark, but not in the USA.
The Danish data showed a 29% increase in the incidence of bipolar disorder among people in areas with the worst air quality.
The data also showed that early childhood exposure to air pollution was linked with a 50% increase in major depression, a 147% increase in schizophrenia, and a 162% increase in personality disorders, when compared with individuals who grew up in areas with the highest quality of air.
- The results suggest an association between neuropsychiatric conditions and exposure to air pollution, especially in the first 10 years of life. However, this is an association, and not a causation. The study cannot conclude that air pollution ’caused’ the conditions.
- The study cannot explain the mechanisms through which air pollution may be leading to the conditions. One hypothesis is that air pollution causes inflammatory and cell–damaging (cytotoxic) effects on the neural tissue. This, in the long term, leads to neuropsychiatric conditions.
- The USA data is about 100 times larger number of people than the Danish data. However, the Danish data can track a person’s pollution exposure down to a square kilometer area, while the USA data is connected to county level pollution, which often is thousands of square kilometer in size.
Read more about this research: Neuropsychiatric disorders linked to environmental pollution exposure.
- Reduce exposure to airborne pollutants.
Especially prevent the air pollution exposure till the age of 10 years.
First published on: 2nd September, 2019
Image credit: Nyamdorj from Pixabay