A quarterly publication of the Autism Research Institute
Summer, 2016 | Number 3, Volume 30
Children exposed to acetaminophen (Tylenol) before birth may have an increased risk for autism spectrum disorders (ASD), according to a new study.
Claudia Avella-Garcia and colleagues recruited more than 2,600 mother-child pairs for their study during the mothers’ pregnancies. They evaluated 88 percent of the children at one year of age, and nearly 80 percent at five years of age.
The researchers determined whether mothers took acetaminophen during pregnancy and, if so, whether they took it sporadically or regularly. Of the children in the study, more than 40 percent were exposed to acetaminophen at some time during the first 32 weeks of pregnancy.
Avella-Garcia and her colleagues found that children exposed prenatally to acetaminophen were more likely to exhibit hyperactivity and impulsive behavior at five years of age. In addition, boys persistently exposed to acetaminophen exhibited more symptoms of autism than unexposed boys.
Study coauthor Jordi Julvez says there are several possible explanations for the team’s findings. “First of all,” he says, “[acetaminophen] relieves pain by acting on cannabinoid receptors in the brain. Since these receptors normally help determine how neurons mature and connect with one another, [the drug] could alter these important processes. It can also affect the development of the immune system, or be directly toxic to some fetuses that may not have the same capacity as an adult to metabolize this drug, or by creating oxidative stress.”
The researchers say that the correlation between acetaminophen use and ASDs in boys but not girls may be linked to sex differences in the metabolism of the drug. “Animal studies have suggested that male mice undergo greater toxicity than female mice after being administered a similar dose of acetaminophen,” they say.
The researchers’ results are consistent with those of an earlier study which reported that mothers who take acetaminophen frequently during pregnancy may be more likely to have children with language and behavior problems. In that study, Ragnhild Eek Brandlistuen and colleagues analyzed data on more than 48,000 women and found that children exposed to prenatal acetaminophen for more than 28 days had poorer gross motor and communication skills. In addition, they exhibited more behavior problems and had higher activity levels.
“Acetaminophen use in pregnancy and neurodevelopment: attention function and autism spectrum symptoms,” Claudia B. Avella-Garcia, Jordi Julvez, Joan Fortuny, Cristina Rebordosa, Raquel García-Esteban, Isolina Riaño Galán, Adonina Tardón, Clara L. Rodríguez-Bernal, Carmen Iñiguez, Ainara Andiarena, Loreto SantaMarina, and Jordi Sunyer, International Journal of Epidemiology, June 28, 2016 (epub prior to print publication). Address: Jordi Julvez, Centre for Research in Environmental Epidemiology-PRBB, C. Doctor Aiguader 88, 08003 Barcelona, Spain, [email protected].
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“Prenatal exposure to paracetamol may increase autism spectrum symptoms,” news release, Oxford University Press, July 1, 2016.
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“Prenatal paracetamol exposure and child neurodevelopment: a sibling-controlled cohort study,” Ragnhild Eek Brandlistuen, Elvind Ystrom, Irena Nulman, Gideon Koren, and Hedvig Nordeng, International Journal of Epidemiology, October 24, 2013 (online). Address: Ragnhild Eek Brandlistuen, Department of Pharmacy, School of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316 Oslo, Norway, r.e.br [email protected].
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“Too much Tylenol in pregnancy could affect child’s development, study finds,” Kathryn Doyle, Reuters, October 24, 2013.
