Antiepileptic monotherapy significantly impairs normative scores on common tests of executive functions

Understanding how antiepileptic (AED) monotherapy influences normative test scores is of importance in the clinic for correct interpretation of neuropsychological profiles. Previous studies have primarily reported minor influence on neuropsychological raw scores, and the clinical relevance of these findings is unclear. Aim of the study - To obtain a clinical valid answer to this question, we analysed changes in T-scores after AED withdrawal in a large group of well-controlled epilepsy patients, for tests previously shown to be sensitive to AED withdrawal. Methods - We report outcomes on measures of choice reaction time from the California Computerized Assessment Package, on the Controlled Oral Word Association Test and on the Stroop Color-Word Interference Test. Results - Significantly improved T-scores were revealed after AED withdrawal on five of the six tests of executive functions with mean improvement of 5 T-scores. Comparable results were achieved in the subgroup taking carbamazepine, with a mean improvement of 6.2 T-scores. Conclusion - The present results suggest that T-scores for computerized tests of choice reaction time and tests of verbal fluency and response inhibition may be significantly impaired as a consequence of AED monotherapy, and that careful interpretation of these scores is required in diagnostic assessment of patients receiving AED monotherapy.