Epilepsy Drug Linked to Babies' Lower IQ
Children Born to Mothers Who Took Valproate Have Lower IQs, Researchers Say
Epilepsy Drugs in Pregnancy and IQ: Study Details continued...
Although the association between epilepsy drugs and birth defects has long been known -- with valproate found to have risks of birth defects two to four times as high as other epilepsy drugs -- the potential link between the drugs and cognitive functioning in the children has been studied much less, Meador says.
His team followed the children for six years to assess intelligence, with the current report focusing on the interim test results on the 309 children at age 3.
Epilepsy Drugs & IQ: Study Results
Children born to mothers who took valproate had the lowest average IQ, Meador's team found, even after adjusting for other factors that might influence IQ, such as a mother's IQ, her age at delivery, or the type of epilepsy.
The average IQs were:
- 101 for children whose mothers took lamotrigine
- 99 for children whose mothers took phenytoin
- 98 for children whose mothers took carbamazepine
- 92 for children whose mothers took valproate
"An average IQ is 100," Meador says, "and below 70 is mentally retarded."
Exactly how valproate lowers IQ is not known, Meador says. "We think the effect may be similar to babies exposed to alcohol in utero," he says, with both substances causing damage of brain cells.
When they looked more closely at the doses of valproate, the researchers found that children born to women who took less than 1,000 milligrams a day of valproate had higher IQs than those who took more than 1,000 milligrams. Those exposed to high doses had an average IQ of 87, and those exposed to lower doses had an average IQ of 97, they found.
Although the researchers found the lower doses of valproate associated with less risk, Meador says he can't pinpoint a "safe" dose.
Even so, the study finding "supports a recommendation that valproate not be used as a first-choice drug in women of childbearing potential," the authors conclude in the report. They reached that conclusion, Meador says, despite the fact that some women with epilepsy respond better to valproate than to other drugs.
Women should not stop any epilepsy drug without consulting their physician, Meador warns.