Abstracts

Rationale: The neurocognitive burden of epilepsy includes not only cognitive impairments but also a high variability of cognitive performance over time as a function of epilepsy related factors. Longitudinal measurements in a pre-post design are among the most informative methods of clinical neuropsychology. We tested specific hypotheses about the causation of longitudinal changes in attention and executive functions in a retrospective cohort of patients with difficult to treat epilepsies. Methods: All patients from our tertiary epilepsy center with at least two assessments using a neuropsychological screening tool for detecting impairments in attention and executive functions were included. Specific evidence-based hypotheses were tested in six non-exclusive groups of patients: (i) Cognitive performance will improve or decline in response to starting or discontinuing of treatment with topiramate. (ii) Cognitive performance will depend on the number of AEDs taken. (iii) In a surgical series of seizure free predominantly temporal lobe epilepsy patients, attention and executive functions will improve, but no major changes of cognitive performances will occur in the postoperative course following resection. Data were analyzed using paired t-tests. Results: According to the hypotheses, (i) cognitive performance did decline following the start of a treatment with topiramate (n=105 patients; p<.000) and improved after discontinuation (n=51 patients; p<.000). (ii) Cognitive performance did improve after reducing the number of AEDs taken (n=40; p <.001) but did not change following an increase of the number of AEDs (n=22; p=.227). (iii) Cognitive performance did not improve following surgery (n=43 patients, p<.32) and did not change in the postoperative course between 6 and 24 months (mean interval: 349 days; n=71 patients; p=.73). Conclusions: On an individual basis, there are a variety of factors that determine cognitive performance. On group level analyses, it is possible to compare the impact of a sample of relevant factors. This study has shown that the biggest impact on cognitive performance relates to treatment with topiramate, followed by the number of AEDs taken. The impact of temporal lobe surgery in this sample was not significant. The results of this study may help counseling patients about reasons for the variability of their cognitive performances over time.