Epilepsy Drug Linked to Babies' Lower IQ
Children Born to Mothers Who Took Valproate Have Lower IQs, Researchers Say
April 15, 2009 -- Women with epilepsy who took the drug valproate (Depakote) during pregnancy gave birth to children whose IQ at age 3 averaged up to 9 points lower than the scores of children exposed to other epilepsy drugs, according to a new study.
"Valproate exposure to the unborn child is associated with a lower IQ, which is not explained by any of the other factors [influencing IQ], such as mother's IQ, mother's age, or epilepsy type," says Kimford J. Meador, MD, the study's lead author and professor of neurology at Emory University in Atlanta.
The average IQ of children born to women who took valproate was 92 -- 8 below the 100 that is considered average -- and the scores of those exposed to other epilepsy drugs ranged from 98 to 101, he tells WebMD.
The implications go beyond the use of the drugs in women of childbearing age who have epilepsy, Meador tells WebMD, because the drug is also commonly prescribed for migraine headaches and bipolar disorder.
In response to the study, published in Wednesday's New England Journal of Medicine, a spokesperson for Abbott, which makes valproate, said the drug may be the only effective medication for some women.
Epilepsy Drugs in Pregnancy and IQ: Study Details
Meador and his colleagues enrolled pregnant women with epilepsy who received care at 25 epilepsy centers in the U.S. and the United Kingdom from late 1999 to early 2004.
About 3 million people in the U.S. have some form of epilepsy, according to the Epilepsy Foundation of America, and experience seizures, which are brief disturbances of electrical activity in the brain. About 25,000 babies are born annually in the U.S. to mothers who have epilepsy.
The researchers gathered information about the type of epilepsy drug taken, the dose, compliance with the medication, the mother's IQ, her age at delivery, race or ethnicity, type of epilepsy, and lifestyle habits such as the use of alcohol, tobacco, and other drugs during pregnancy.
The women in the study took one of four drugs: valproate (Depakote), lamotrigine (Lamictal), carbamazepine (Tegretol), or phenytoin (Dilantin).
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.