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Maternal epilepsy and offsprings' adult intelligence: a population-based study from Norway.

Oyen N, Vollset SE, Eide MG, Bjerkedal T, Skjaerven R

Department of Public Health and Primary Health Care, University of Bergen, Bergen, Norway. noy@ssi.dk

PURPOSE: We examined if children of mothers with epilepsy had normal intelligence, speculating that either epilepsy or its therapy might affect this parameter. METHODS: In a population-based cohort study in Norway, information on maternal epilepsy reported to the Medical Birth Registry of Norway, 1967-1979 was linked to information on 18-19-year-old men's intellectual ability and anthropometric measures ascertained by the Norwegian Conscripts Service, 1984-1999. The standardized intelligence test (IQ score) was reported as single-digit standard scores with values from 1 to 9. No individual information on antiepileptic drug therapy was available. RESULTS: Mean IQ score was lower in 1,207 conscripts whose mothers had epilepsy reported on the birth notification form, as compared with 316,554 conscripts of mothers without epilepsy; 4.8 (standard deviation 1.8) versus 5.2(1.8), p < 0.001, respectively. This difference remained after adjustment for maternal education, maternal age, birth order, marital status, year of birth, and weight and length at birth. When comparing men with and without reported maternal epilepsy, the odds ratio of having an IQ score < or = 3 was 1.6 (95% confidence interval: 1.4-1.8), which was unaffected by adjustment for confounding factors. Mean height among conscripts of mothers with and without epilepsy measured 178.6 and 179.9 cm, respectively, a difference of 1.3 cm (p < 0.001). CONCLUSIONS: We observed that almost 20 years after birth, maternal epilepsy was associated with reduced IQ score and also shorter adult height in male offspring. We do not know whether these findings will persist when epilepsy is better treated with the newer and safer generation of antiepileptic drugs.

Published 10 September 2007 in Epilepsia, 48(9): 1731-8.
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