Differential cognitive effects of antiepileptic drugs.

As a group, children and adolescents with epilepsy have a higher prevalence of cognitive and behavioral disorders, although many fall within the normal distribution. For those affected, several causes have been identified, some of which may be interrelated. It has proven to be methodologically sound to isolate the role of specific antiepileptic drugs as a cause of cognitive impairment. The large body of literature that has accumulated on this topic is characterized by a relatively high proportion of inconclusive or contradictory observations. This may be due in part to the many methodological pitfalls in this area of research. The emerging picture is that cognitive effects caused by antiepileptic drugs are neither the rule nor the exception. Although certain drugs appear more likely to be involved, no single drug causes problems in every patient, and no drug can be assumed never to cause any cognitive impairment. The subgroup of patients that are at higher risk cannot be easily defined. Early detection of cognitive effects is based on actively eliciting reports of symptoms. This can be complemented by a screening battery in case of suspicion.