Autism has been growing at an alarming rate, and a new study suggests that air pollution may be a major contributor, at least in people who already have a genetic predisposition towards the disorder.
"Our research shows that children with both the risk genotype and exposure to high air pollutant levels were at increased risk of autism spectrum disorder compared to those without the risk genotype and lower air pollution exposure," said the study's first author, Heather E. Volk, Ph.D., M.P.H., assistant professor of research in preventive medicine and pediatrics at the Keck School of Medicine at the University of Southern California.
Autism is a physical condition linked to abnormal biology and chemistry in the brain. Just a few years ago, the Centers for Disease Control and Prevention (CDC) estimated one in 88 school children had some form of autism. Now, the CDC estimates the prevalence is closer to one in 50.
The USC study, "Autism spectrum disorder: Interaction of air pollution with the MET receptor tyrosine kinase gene," is scheduled to appear in the January 2014 edition of Epidemiology.
"Although gene-environment interactions are widely believed to contribute to autism risk, this is the first demonstration of a specific interaction between a well-established genetic risk factor and an environmental factor that independently contribute to autism risk," said Daniel B. Campbell, Ph.D., assistant professor of psychiatry and the behavioral sciences at the Keck School of Medicine of USC and the study's senior author.
Campbell and Volk's team studied 408 children between 2 and 5 years of age from the Childhood Autism Risks From Genetics and the Environment Study, a population-based, case-control study of preschool children from California. Of those, 252 met the criteria for autism or autism spectrum disorder. Air pollution exposure was determined based on the past residences of the children and their mothers, local traffic-related sources, and regional air quality measures. MET genotype was determined through blood sampling.