Prenatal Exposure to Paracetamol May Increase Autism Spectrum Symptoms

OXFORD, United Kingdom -- July 1, 2016 -- Prenatal exposure to paracetamol is strongly associated with autism spectrum symptoms in boys and is related to attention-related and hyperactivity symptoms in both boys and girls, according to a study published in the International Journal of Epidemiology.

The study found a 30% increase in the risk of detriment to some attention functions, and an increase of 2 clinical symptoms of autism spectrum symptoms in boys.

Claudia Avella-Garcia, CREAL, Barcelona, Spain, and colleagues recruited 2,644 mother-child pairs in a birth cohort study during pregnancy. Of the children in the study, 88% were evaluated when the child was aged 1 year and 79.9% were evaluated at age 5.

Mothers were asked about their use of paracetamol during pregnancy and the frequency of use was classified as never, sporadic, or persistent. Exact doses could not be noted due to mothers being unable to recall them exactly.

Of the children evaluated at age 1 year, 43% were exposed to any paracetamol at some point during the first 32 weeks of pregnancy.

When assessed at age 5, exposed children were at higher risk of hyperactivity or impulsivity symptoms. Persistently exposed children in particular showed poorer performance on a computerised test measuring inattention, impulsivity and visual speed processing.

Boys also showed more autism spectrum symptoms when persistently exposed to paracetamol.

“Although we measured symptoms and not diagnoses, an increase in the number of symptoms that a child has, can affect him or her, even if they are not severe enough to warrant a clinical diagnosis of a neurodevelopmental disorder,” said Dr. Avella-Garcia.

“Paracetamol could be harmful to neurodevelopment for several reasons,” said co-author Jordi Júlvez, MD, CREAL. “First of all, it relieves pain by acting on cannabinoid receptors in the brain. Since these receptors normally help determine how neurons mature and connect with one another, paracetamol 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 metabolise this drug, or by creating oxidative stress.”

There could also be an explanation for why boys are more likely to have autism spectrum symptoms.

“The male brain may be more vulnerable to harmful influences during early life,” said Dr. Avella-Garcia. “Our differing gender results suggest that androgenic endocrine disruption, to which male brains could be more sensitive, may explain the association.”

The authors stressed that further studies should be conducted with more precise dosage measurements, and that the risks versus benefits of paracetamol use during pregnancy and early life should be assessed before treatment recommendations are made.

SOURCE: Oxford University Press
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