The cognitive phenotype of idiopathic generalized epilepsy

Dysexecutive traits have been described in idiopathic generalized epilepsy (IGE), but studies mainly focused on juvenile myoclonic epilepsy (JME). To better understand the neuropsychology of IGE, more research is needed on syndromes other than JME, controlling potential confounding factors as the cognitive effects of valproate and epileptic discharges (ED). We describe the neuropsychological profile of a group of patients with different syndromes of IGE including simultaneous video electroencephalography (EEG).

We performed a comprehensive cognitive and neuropsychiatric evaluation with video-EEG on 61 adults with IGE (JME 19; IGE with generalized tonic-clonic seizures [GTCS] alone [IGE-GTCS] 22; childhood absence epilepsy [CAE] or juvenile absences epilepsy [JAE] persisting in adulthood 20). We compared results between patients (globally and by syndrome) and a control group of 21 individuals (similar age, educational level); p-values were adjusted for multiple testing according to a 0.05 false discovery rate.

Patients obtained significantly lower results than controls on visuospatial working memory, processing speed, cognitive flexibility and strategy, abstract visuospatial reasoning, arithmetic, and acquired knowledge. While CAE/JAE showed the lowest scores on cognitive assessment and highest anxiety index, IGE-GTCS showed the most favorable scores. Most tests were not influenced by valproate intake, and the dose did not correlate with cognitive performance in the test that yielded differences between patients and controls. Epileptic discharges during assessment were not frequent (10 patients, 1-4 tests).

Our findings suggest that patients with IGE have significantly lower abilities in various executive functions and acquired knowledge, compared to population of same age and education. The low frequency of ED on simultaneous video-EEG and absence of correlation of scores with valproate dose reinforce that the obtained results are due to a cognitive phenotype in IGE. This phenotype may be influenced by syndrome, and patients with CAE/JAE persisting in the adult may have a wider neuropsychiatric impairment.