Prenatal exposure to air pollution associated with increased mental health risks: Study

Exposure to air pollution during pregnancy is linked to the development of mental health issues in adolescence, according to new research. The University of Bristol-led study, published in JAMA Network Open, investigated the long-term mental health effects of early-life exposure to air and noise pollution.

There is growing evidence indicating that air pollution, consisting of toxic gases and particulate matter, may play a significant role in the onset of mental health issues. Researchers believe that pollution can adversely impact mental health through several mechanisms. These include compromising the blood-brain barrier, promoting neuroinflammation and oxidative stress, and directly entering the brain, causing tissue damage.

The blood-brain barrier is a protective shield that prevents harmful substances in the bloodstream from entering the brain. However, pollutants can weaken this barrier, allowing toxins to penetrate brain tissue and potentially disrupt normal brain function. Neuroinflammation, an inflammatory response within the brain, can be triggered by these pollutants, leading to neuronal damage and contributing to mental health disorders.

In the study, researchers examined the long-term effects of air and noise pollution exposure during pregnancy, early childhood, and adolescence on three common mental health issues: psychotic experiences, depression, and anxiety. Using data from over 9,000 participants in Bristol’s Children of the 90s birth cohort study, which followed over 14,000 pregnant women recruited between 1991 and 1992 and their children, researchers linked early childhood data with mental health reports at ages 13, 18, and 24. This allowed them to map mental health outcomes against outdoor air and noise pollution exposure.

The results showed that small increases in fine particulate matter (PM2.5) during pregnancy and childhood were linked to more psychotic experiences and depression symptoms in teenagers and young adults.

Specifically, every 0.72 micrograms per cubic meter increase in PM2.5 during pregnancy and childhood was linked to an 11% higher chance of psychotic experiences and a 10% higher chance of depression.

"Childhood, adolescence, and early adulthood are key periods for developing psychiatric disorders, with nearly two-thirds of affected individuals becoming unwell by age 25. Our findings contribute to growing evidence that air and noise pollution negatively impact mental health. This is concerning because air pollution is widespread, and mental health issues are increasing globally. Since pollution is preventable, interventions like low emissions zones could improve mental health, particularly for vulnerable groups like pregnant women and children. Although these findings don't prove causation, recent studies show that low emissions zones can positively impact mental health,” said Dr Joanne Newbury, the study’s lead author.

Reference: Newbury JB, Heron J, Kirkbride JB, et al. Air and Noise Pollution Exposure in Early Life and Mental Health From Adolescence to Young Adulthood. JAMA Network Open. 2024;7(5):e2412169. doi:10.1001/jamanetworkopen.2024.12169