Air pollution exposure in childhood linked to schizophrenia risk, finds study

Air pollution affects physical health, and research results now conclude that it also affects our psychological health. Children who are exposed to higher levels of air pollution while growing up have an increased risk of developing schizophrenia, a study has found.

The study combined genetic data from iPSYCH with air pollution data from the Department of Environmental Science to show that the higher the level of air pollution, the higher the risk of schizophrenia. For each 10 mg/m3 (concentration of air pollution per cubic metre) increase in the daily average, the risk of schizophrenia increases by approximately twenty percent.

"Children who are exposed to an average daily level above 25 mg/m3 have an approx. sixty percent greater risk of developing schizophrenia compared to those who are exposed to less than 10 mg/m3," explained Senior Researcher Henriette Thisted Horsdal, who is behind the study.

The results of the study have been published in the scientific journal JAMA Network Open.

To put these figures into perspective, the lifetime risk of developing schizophrenia is approximately two percent, which equates to two out of a hundred people developing schizophrenia during their life.

For people exposed to the lowest level of air pollution, the lifetime risk is just under two percent, while the lifetime risk for those exposed to the highest level of air pollution is approximately three 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. 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," said Henriette Thisted Horsdal about the study, which is the first of its kind to combine air pollution and genetics in relation to the risk of developing schizophrenia.

The study included 23,355 people in total, and of these, 3,531 developed schizophrenia. Though the results demonstrate an increased risk of schizophrenia when the level of air pollution during childhood increases, the researchers cannot comment on the cause.

Instead, they emphasise that further studies are needed before they can identify the cause of this association.