The most recent study, published online in The Lancet Neurology (1/23/13), studied 311 children whose IQ was assessed at six years of age. Researchers found that the average IQ among children exposed to valproate (the generic name for Depakote) prior to birth was 97, whereas the average IQ of children exposed to other antiepileptic drugs was 105 or higher.
Researchers found that the effect of valproate on IQ was dose dependent, meaning the higher the dose, the greater the effect on the children’s IQ. Children exposed to less than 1000 mg per day had IQ levels similar to children exposed to other antiepileptic drugs. Among the cognitive abilities tested were verbal ability and memory.
“Children exposed to valproate did poorly on measures of verbal and memory abilities compared with those exposed to the other antiepileptic drugs,” researchers wrote. They concluded, “Fetal valproate exposure has dose-dependent associations with reduced cognitive abilities across a range of domains at 6 years of age.”
READ MORE DEPAKOTE BIRTH DEFECT LEGAL NEWS
The same children were reportedly used in a similar study at three years of age, to determine the effects of valproate on their cognitive abilities. The outcome of that study resulted in the US Food and Drug Administration (FDA) issuing a warning that exposure to valproate prior to birth was associated with impaired cognitive functions. At the time, the FDA noted that the long-term effects of valproate on IQ and cognitive development are not known.
Valproate has also been linked to an increased risk of neural tube birth defects.