Literature Review

In Utero Valproate Exposure May Increase Risk of Autism Symptoms



An elevated rate of autism traits was seen among a cohort of children exposed to antiepileptic drugs (AEDs) in utero. Study findings were reported in the July Epilepsia. “The most important determinant of association with autistic traits was higher doses of sodium valproate exposure,” said Amanda G. Wood, PhD, MPsych, a Senior Lecturer in the School of Psychology at the University of Birmingham in the United Kingdom.

While the use of valproate in women who may become pregnant is generally avoided, there are insufficient data regarding the risk of autism spectrum disorders with low-dose valproate. “If this risk is no greater than with other AEDs, it may enable women with genetic generalized epilepsy to retain optimal seizure control as well as minimize harm to their unborn child,” Dr. Wood said.

Dr. Wood and colleagues conducted a prospective cohort study in children exposed to anticonvulsants during pregnancy, with all assessments conducted by examiners who were blinded to drug-exposure status. Participants were 105 Australian children ages 6 to 8 who were recruited through the Australian Pregnancy Register for Women on Antiepileptic Medication. Maternal epilepsy, pregnancy, and medical history data were obtained prospectively. Autism traits were assessed using the Childhood Autism Rating Scale (CARS).

Among the cohort, 11 children (10.5%) had elevated CARS scores, and this proportion was substantially higher than the estimated prevalence of autism spectrum disorders in age-matched children nationally or internationally. Linear regression analysis showed that the mean valproate dose during pregnancy was a significant predictor of CARS scores after controlling for polytherapy, mean carbamazepine dose, folic acid use, seizures during pregnancy, tobacco and marijuana use, maternal IQ, and socioeconomic status.

Children who had in utero exposure to valproate were most likely to have elevated CARS scores, with 7.7% of the valproate monotherapy group and 46.7% of the valproate polytherapy group displaying autism spectrum disorder symptoms. The dose of valproate taken during pregnancy was found to be an independent risk factor for elevated CARS scores, whereas polytherapy was not. “CARS scores were not elevated in children exposed to polytherapy without valproate, suggesting that valproate, or valproate dose, rather than polytherapy per se, is the critical determinant of the relationship,” the researchers said.

Glenn S. Williams

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