Effect of early versus late onset of major motor epilepsy on cognitive-intellectual performance: further considerations.

Two groups of adult patients, one with early (0-5 years), the other with late (10-15 years) age of seizure onset, were compared on 14 variables derived from the Wechsler Adult Intelligence Scale (WAIS) and Halstead's neuropsychological measures. The groups were matched for duration of the disorder and seizure frequency, and all subjects (Ss) had unequivocal histories of major motor seizures. The group with early age of onset obtained significantly lower WAIS, Verbal IQ, Performance IQ, and Full Scale IQ values than the group with late age of onset. No significant intergroup differences were obtained on Halstead's measures, although the performances of both groups were impaired vis-a-vis non-neurological control expectancy. The results suggest that early onset age, as operationally defined in this study, has a specifc differential influence which is restricted to psychometric intellectual functions as measured by the WAIS in groups matched for seizure duration and seizure frequency.