Philadelphia, March 8, 2018 - A new study performed in the Netherlands has linked exposure to residential air pollution during fetal life with brain abnormalities that may contribute to impaired cognitive function in school-age children. The study, published in Biological Psychiatry, reports that the air pollution levels related to brain alterations were below those considered to be safe.

"We observed brain development effects in relationship to fine particles levels below the current EU limit," said lead author Mònica Guxens, MD, of Barcelona Institute for Global Health (ISGlobal), Spain, a center supported by the "la Caixa" Foundation, and Erasmus University Medical Center, the Netherlands. This finding adds to previous studies that have linked acceptable air pollution levels with other complications including cognitive decline and fetal growth development. "Therefore, we cannot warrant the safety of the current levels of air pollution in our cities," said Dr. Guxens.

Exposure to fine particles during fetal life was associated with a thinner outer layer of the brain, called the cortex, in several regions. The study showed that these brain abnormalities contribute in part to difficulty with inhibitory control--the ability to regulate self-control over temptations and impulsive behavior--which is related to mental health problems such as addictive behavior and attention-deficit/hyperactivity disorder.

The study used a population-based cohort in the Netherlands, which enrolled pregnant women and followed the children from fetal life onward. Dr. Guxens and colleagues assessed air pollution levels at home during the fetal life of 783 children. The data were collected by air pollution monitoring campaigns, and included levels of nitrogen dioxide (a prominent air pollutant caused by traffic and cigarette smoking), coarse particles, and fine particles.

Brain imaging performed when the children were between 6 and 10 years old revealed abnormalities in the thickness of the brain cortex of the precuneus and rostral middle frontal region. Despite the relationship between these brain structure alterations and fine particle exposure, the average residential levels of fine particles in the study were well below the current acceptable limit set by the EU--only 0.5 percent of the pregnant women in the study were exposed to levels considered unsafe. The average residential levels of nitrogen dioxide were right at the safe limit.

"Air pollution is so obviously bad for lungs, heart, and other organs that most of us have never considered its effects on the developing brain. But perhaps we should have learned from studies of maternal smoking that inhaling toxins may have lasting effects on cognitive development," said John Krystal, MD, Editor of Biological Psychiatry.

The fetal brain is particularly vulnerable during pregnancy--it hasn't yet developed the mechanisms to protect against or remove environmental toxins. The findings of the study suggest that exposure to levels even below those considered safe could cause permanent brain damage.

"Although specific individual clinical implications of these findings cannot be quantified, based on other studies, the observed cognitive delays at early ages could have significant long-term consequences such as increased risk of mental health disorders and low academic achievement, in particular due to the ubiquity of the exposure," said Dr. Guxens.

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Notes for editors

The article is "Air pollution exposure during fetal life, brain morphology, and cognitive function in school-age children," by Mònica Guxens, Ma?gorzata J. Lubczy?ska, Ryan Muetzel, Albert Dalmau-Bueno, Vincent W.V. Jaddoe, Gerard Hoek, Aad van der Lugt, Frank C. Verhulst, Tonya White, Bert Brunekreef, Henning Tiemeier, and Hanan El Marroun (https:/ / doi. org/ 10. 1016/ j. biopsych. 2018. 01. 016 ). It appears in Biological Psychiatry, published by Elsevier.

Copies of this paper are available to credentialed journalists upon request; please contact Rhiannon Bugno at Biol.Psych@UTSouthwestern.edu or +1 214 648 0880. Journalists wishing to interview the authors may contact Mònica Guxens, MD, at monica.guxens@isglobal.org.

The authors' affiliations and disclosures of financial and conflicts of interests are available in the article.

John H. Krystal, MD, is Chairman of the Department of Psychiatry at the Yale University School of Medicine, Chief of Psychiatry at Yale-New Haven Hospital, and a research psychiatrist at the VA Connecticut Healthcare System. His disclosures of financial and conflicts of interests are available here.

About Biological Psychiatry

Biological Psychiatry is the official journal of the Society of Biological Psychiatry, whose purpose is to promote excellence in scientific research and education in fields that investigate the nature, causes, mechanisms and treatments of disorders of thought, emotion, or behavior. In accord with this mission, this peer-reviewed, rapid-publication, international journal publishes both basic and clinical contributions from all disciplines and research areas relevant to the pathophysiology and treatment of major psychiatric disorders.

The journal publishes novel results of original research which represent an important new lead or significant impact on the field, particularly those addressing genetic and environmental risk factors, neural circuitry and neurochemistry, and important new therapeutic approaches. Reviews and commentaries that focus on topics of current research and interest are also encouraged.

Biological Psychiatry is one of the most selective and highly cited journals in the field of psychiatric neuroscience. It is ranked 6th out of 142 Psychiatry titles and 10th out of 258 Neurosciences titles in the Journal Citations Reports® published by Thomson Reuters. The 2016 Impact Factor score for Biological Psychiatry is 11.412.

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Biol.Psych@UTSouthwestern.edu