Air pollution may make kids more prone to schizophrenia: Study

Kids who grow up in areas with heavy air pollution have a higher risk of developing schizophrenia, according to a study which suggests that particulate matter in air may not only harm physical well-being, but also mental health.

The study, published in the Journal of the American Medical Association (JAMA), assessed genetic data from iPSYCH -- a project to find the basis and treatment of the most common and serious mental illnesses, including autism, bipolar disorder, and depression.

The researchers, including those from Aarhus University in Denmark, combined the iPSYCH data with information on air pollution from the country's Department of Environmental Science.

According to the study, children who are exposed to a high level of air pollution while growing up, have an increased risk of developing schizophrenia -- a chronic and severe mental disorder which affects how a person thinks, feels, and behaves.

For each 10 microgramme per cubic metre (g/m3) increase in the daily average of air pollution, the risk of schizophrenia increased by a fifth, the researchers reported in the study.

"Children who are exposed to an average daily level above 25 g/m3 have an approximately 60 per cent greater risk of developing schizophrenia compared to those who are exposed to less than 10 g/m3," explained study co-author Henriette Thisted Horsdal from Aarhus University.

To put the findings in perspective, the researchers said the lifetime risk of developing schizophrenia is approximately two per cent for people, but for those exposed to the highest level of air pollution, this risk is three per cent.

"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," she added.

Further studies are needed to identify the cause of this association, the scientists said.