A new Danish study shows that individuals who were exposed to a high level of air pollution during childhood are at greater risk of developing schizophrenia.
The findings are published in the scientific journal JAMA Network Open.
“The study shows that the higher the level of air pollution, the higher the risk of schizophrenia,” said senior researcher Dr. Henriette Thisted Horsdal from Aarhus University. “For each 10 μg/m3 (concentration of air pollution per cubic metre) increase in the daily average, the risk of schizophrenia increases by approximately twenty per cent.”
“Children who are exposed to an average daily level above 25 μg/m3 have an approximately 60 percent greater risk of developing schizophrenia compared to those who are exposed to less than 10 μg/m3.”
To put these figures into perspective, the lifetime risk of developing schizophrenia is about 2 percent, which equates to two out of 100 people developing schizophrenia during their life. For those exposed to the lowest level of air pollution, the lifetime risk is just under 2 percent, while the lifetime risk for those exposed to the highest level of air pollution is about 3 percent.
“The risk of developing schizophrenia is also higher if you have a higher genetic liability for the disease. Our data shows that these associations are independent of each other,” Horsdal said. “The association between air pollution and schizophrenia cannot be explained by a higher genetic liability in people who grow up in areas with high levels of air pollution.”
The research involved a total of 23,355 people, of which 3,531 developed schizophrenia. Though the findings reveal an increased risk of schizophrenia when the level of air pollution during childhood increases, the researchers emphasize that more research is needed before they can identify what is driving this association.
The study combined air pollution data from the Department of Environmental Science with genetic data from iPSYCH, a Danish research project focused on finding the causes of major mental disorders. The study is the first of its kind to combine air pollution and genetics in relation to the risk of developing schizophrenia.
Source: Aarhus University