The effect of early versus late onset of major motor epilepsy upon cognitive-intellectual performance.

Performance on the Wechsler Adult Intelligence Scale and Halstead neuropsychological measures were investigated in two groups of adult subjects with major motor epilepsy of early (0 to 5 yr) and later (17 to 50 yr) onset, and in two groups with early and later onset of brain damage without epilepsy. The two groups with early onset earned poorer scores on most tests than did the two groups with later onset. The findings suggest an adverse effect of cerebral dysfunction of early onset, whether accompanied by major motor seizures or not. Subjects with early onset of major motor seizures scored significantly lower on 9 of 14 measures than subjects in any other group, none of which showed significant intergroup differences in the dependent variables employed. The results support the conclusion that early age of onset of major motor seizures is more apt to result in impairment of mental abilities in adult life than is later onset of seizures or early or late onset of brain damage uncomplicated by epilepsy.