Do seizures in children cause intellectual deterioration?

We studied whether the occurrence of seizures in childhood affected intellectual performance. We compared the full-scale IQs at seven years of age of children who had experienced one or more nonfebrile seizures with the IQs of their seizure-free siblings who were tested at the same age in a large longitudinal study. Among 98 children with seizures, the mean score on IQ tests at seven years was not significantly different from the mean score of their siblings. Mental retardation was more common among the children with seizures, but the excess was accounted for by children who had neurologic abnormalities before the first seizure. We also examined the IQ before and after the onset of seizures in 62 children whose first seizure occurred in the interval between psychometric examinations given at four and seven years of age. The IQ at seven years in the children with seizures did not differ significantly from that in controls matched for IQ (as determined at the four-year assessment), sex, race, and socioeconomic status. Thus, in both the sibling-control comparison and the comparisons made between controls and subjects before and after the onset of seizures, the occurrence of nonfebrile seizures was not associated with a significant change in full-scale IQ.