Cognitive effects of long-term treatment with phenobarbital and valproic acid in school children.

The Wechsler Intelligence Scales for Children was applied to 64 epileptic children and 60 healthy subjects; patients followed chronic treatment with valproic acid (n = 32) or phenobarbital (n = 32). None of the children suffered mental retardation or neurological abnormalities. The test was repeated after a 9-12 month interval: 26 of the valproate treated children and 23 of the phenobarbital-treated children performed the second evaluation. At baseline, total, verbal and performance IQ scores of children receiving phenobarbital were lower than those of controls. When the results of the first and the second tests were compared, a significant increase in IQ scores was detected among controls and patients treated with valproic acid, but not among phenobarbital-treated patients. It is concluded that long-term phenobarbital therapy induces a significant impairment in learning ability whereas long-term valproate therapy does not exert a noticeable noxious effect at this respect.