Progressive cognitive decline in adolescents and adults with epilepsy.

The effects of an accumulation of single seizures upon mental abilities in adolescents and adults is explored through a selective review of the world's literature. The papers reviewed were divided up into cross-sectional and longitudinal studies. Of 16 investigations meeting all requirements for inclusion, 12 produced results pointing to a relationship between seizures and adverse cognitive change. The cross-sectional studies produced stronger results than the longitudinal ones, no doubt because the effects of co-existing factors not related to seizure effects were included in measures of cognitive decline. The longitudinal investigations showed mild but definite relationships between seizures and mental decline. However, relationships could be found only with generalized tonic-clonic seizures and not with partial attacks. Results of an original investigation were reported which were consistent with the literature review. Suggestions for future research were offered.