Interictal cognitive aspects of epilepsy.

Common methodological problems in the assessment of interictal cognitive deficits in epilepsy include limitations in neuropsychological tests selected and subject sampling problems. Neuropsychological functioning is related to a series of seizure history variables with an emphasis on those seizure factors showing the closest relationships. However, even these relationships are limited in scope, and it has been noted that no study has used multivariate procedures to demonstrate maximal relationships with measures of mental abilities. This technique was applied to data on 487 cases, and slightly stronger relationships were produced. However, this still did not account for the vast majority of the variance in cognitive tests. Conclusions concerning neuropsychological functioning in epilepsy require careful attention to sampling problems and other factors, and seizure history variables have only limited relationships with cognitive functioning, even when they are combined in an optimal fashion.