Summary Background Many women of childbearing potential take antiepileptic drugs, but the cognitive effects of fetal exposure are uncertain. We aimed to assess effects of commonly used antiepileptic drugs on cognitive outcomes in children up to 6 years of age. Methods In this prospective, observational, assessor-masked, multicentre study, we enrolled pregnant women with epilepsy on antiepileptic drug monotherapy (carbamazepine, lamotrigine, phenytoin, or valproate) between October, 1999, and February, 2004, at 25 epilepsy centres in the UK and the USA. Our primary outcome was intelligence quotient (IQ) at 6 years of age (age-6 IQ) in all children, assessed with linear regression adjusted for maternal IQ, antiepileptic drug type, standardised dose, gestational birth age, and use of periconceptional folate. We also assessed multiple cognitive domains and compared findings with outcomes at younger ages. This study is registered with ClinicalTrials.gov, number NCT00021866. Findings We included 305 mothers and 311 children (six twin pairs) in the primary analysis. 224 children completed 6 years of follow-up (6-year-completer sample). Multivariate analysis of all children showed that age-6 IQ was lower after exposure to valproate (mean 97, 95% CI 94–101) than to carbamazepine (105, 102–108; p=0·0015), lamotrigine (108, 105–110; p=0·0003), or phenytoin (108, 104–112; p=0·0006). Children exposed to valproate did poorly on measures of verbal and memory abilities compared with those exposed to the other antiepileptic drugs and on non-verbal and executive functions compared with lamotrigine (but not carbamazepine or phenytoin). High doses of valproate were negatively associated with IQ (r=−0·56, p<0·0001), verbal ability (r=−0·40, p=0·0045), non-verbal ability (r=−0·42, p=0·0028), memory (r=−0·30, p=0·0434), and executive function (r=−0·42, p=0·0004), but other antiepileptic drugs were not. Age-6 IQ correlated with IQs at younger ages, and IQ improved with age for infants exposed to any antiepileptic drug. Compared with a normative sample (173 [93%] of 187 children), right-handedness was less frequent in children in our study overall (185 [86%] of 215; p=0·0404) and in the lamotrigine (59 [83%] of 71; p=0·0287) and valproate (38 [79%] of 40; p=0·0089) groups. Verbal abilities were worse than non-verbal abilities in children in our study overall and in the lamotrigine and valproate groups. Mean IQs were higher in children exposed to periconceptional folate (108, 95% CI 106–111) than they were in unexposed children (101, 98–104; p=0·0009). Interpretation Fetal valproate exposure has dose-dependent associations with reduced cognitive abilities across a range of domains at 6 years of age. Reduced right-handedness and verbal (vs non-verbal) abilities might be attributable to changes in cerebral lateralisation induced by exposure to antiepileptic drugs. The positive association of periconceptional folate with IQ is consistent with other recent studies. Funding US National Institutes of Health, UK Epilepsy Research Found...

BACKGROUND-Fetal exposure of animals to antiepileptic drugs at doses lower than those required to produce congenital malformations can produce cognitive and behavioral abnormalities, but cognitive effects of fetal exposure of humans to antiepileptic drugs are uncertain.

We previously reported that foetal valproate exposure impairs intelligence quotient. In this follow-up investigation, we examined dose-related effects of foetal antiepileptic drug exposure on verbal and non-verbal cognitive measures. This investigation is an ongoing prospective observational multi-centre study in the USA and UK, which has enrolled pregnant females with epilepsy on monotherapy from 1999 to 2004. The study seeks to determine if differential long-term neurodevelopmental effects exist across four commonly used drugs (carbamazepine, lamotrigine, phenytoin and valproate). This report compares verbal versus non-verbal cognitive outcomes in 216 children who completed testing at the age of three years. Verbal and non-verbal index scores were calculated from the Differential Ability Scales, Preschool Language Scale, Peabody Picture Vocabulary Test and Developmental Test of Visual-Motor Integration. Verbal abilities were lower than non-verbal in children exposed in utero to each drug. Preconceptional folate use was associated with higher verbal outcomes. Valproate was associated with poorer cognitive outcomes. Performance was negatively associated with valproate dose for both verbal and non-verbal domains and negatively associated with carbamazepine dose for verbal performance. No dose effects were seen for lamotrigine and phenytoin. Since foetal antiepileptic drug exposure is associated with lower verbal than non-verbal abilities, language may be particularly susceptible to foetal exposure. We hypothesize that foetal drug exposure may alter normal cerebral lateralization. Further, a dose-dependent relationship is present for both lower verbal and non-verbal abilities with valproate and for lower verbal abilities with carbamazepine. Preconceptional folate may improve cognitive outcomes. Additional research is needed to confirm these findings, extend the study to other drugs, define the risks associated with drug treatment for seizures in the neonates, and understand the underlying mechanisms.

IMPORTANCE Breastfeeding is known to have beneficial effects, but concern exists that breastfeeding during maternal antiepileptic drug (AED) therapy may be harmful. We previously noted no adverse effects of breastfeeding associated with AED use on IQ at age 3 years, but IQ at age 6 years is more predictive of school performance and adult abilities. OBJECTIVES To examine the effects of AED exposure via breastfeeding on cognitive functions at age 6 years. DESIGN, SETTING, AND PARTICIPANTS Prospective observational multicenter study of long-term neurodevelopmental effects of AED use. Pregnant women with epilepsy receiving monotherapy (ie, carbamazepine, lamotrigine, phenytoin, or valproate) were enrolled from October 14, 1999, through April 14, 2004, in the United States and the United Kingdom. At age 6 years, 181 children were assessed for whom we had both breastfeeding and IQ data. All mothers in this analysis continued taking the drug after delivery. MAIN OUTCOMES AND MEASURES Differential Ability Scales IQ was the primary outcome. Secondary measures included measures of verbal, nonverbal, memory, and executive functions. For our primary analysis, we used a linear regression model with IQ at age 6 years as the dependent variable, comparing children who breastfed with those who did not. Similar secondary analyses were performed for the other cognitive measures. RESULTS In total, 42.9% of children were breastfed a mean of 7.2 months. Breastfeeding rates and duration did not differ across drug groups. The IQ at age 6 years was related to drug group (P italic> .001 [adjusted IQ worse by 7–13 IQ points for valproate compared to other drugs]), drug dosage (regression coefficient, −0.1; 95% CI, −0.2 to 0.0; P = .01 [higher dosage worse]), maternal IQ (regression coefficient, 0.2; 95% CI, 0.0 to 0.4; P = .01 [higher child IQ with higher maternal IQ]), periconception folate use (adjusted IQ 6 [95% CI, 2–10] points higher for folate, P = .005), and breastfeeding (adjusted IQ 4 [95% CI, 0–8] points higher for breastfeeding, P = .045). For the other cognitive domains, only verbal abilities differed between the breastfed and nonbreastfed groups (adjusted verbal index 4 [95% CI, 0–7] points higher for breastfed children, P = .03). CONCLUSIONS AND RELEVANCE No adverse effects of AED exposure via breast milk were observed at age 6 years, consistent with another recent study at age 3 years. In our study, breastfed children exhibited higher IQ and enhanced verbal abilities. Additional studies are needed to fully delineate the effects of all AEDs. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00021866

The Neurodevelopmental Effects of Antiepileptic Drugs (NEAD) study is a prospective observational multicenter study in the USA and UK, which enrolled pregnant women with epilepsy on antiepileptic drug (AED) monotherapy from 1999 to 2004. The study aimed to determine if differential long-term neurodevelopmental effects exist across four commonly used AEDs (carbamazepine, lamotrigine, phenytoin, and valproate). In this report, we examine fetal AED exposure effects on adaptive and emotional/behavioral functioning at 6 years of age in 195 children (including three sets of twins) whose parent (in most cases, the mother) completed at least one of the rating scales. Adjusted mean scores for the four AED groups were in the low average to average range for parent ratings of adaptive functioning on the Adaptive Behavior Assessment System—Second Edition (ABAS-II) and for parent and teacher ratings of emotional/behavioral functioning on the Behavior Assessment System for Children (BASC). However, children whose mothers took valproate during pregnancy had significantly lower General Adaptive Composite scores than the lamotrigine and phenytoin groups. Further, a significant dose-related performance decline in parental ratings of adaptive functioning was seen for both valproate and phenytoin. Children whose mothers took valproate were also rated by their parents as exhibiting significantly more atypical behaviors and inattention than those in the lamotrigine and phenytoin groups. Based upon BASC parent and teacher ratings of attention span and hyperactivity, children of mothers who took valproate during their pregnancy were at a significantly greater risk for a diagnosis of ADHD. The increased likelihood of difficulty with adaptive functioning and ADHD with fetal valproate exposure should be communicated to women with epilepsy who require antiepileptic medication. Finally, additional research is needed to confirm these findings in larger prospective study samples, examine potential risks associated with other AEDs, better define the risks to the neonate that are associated with AEDs for treatment of seizures, and understand the underlying mechanisms of adverse AED effects on the immature brain.