Abstracts

Rationale: Patients with Juvenile Myoclonic Epilepsy (JME) appear to be less able to learn from previous experience. They often present with risk-taking and impulsive behaviour, suggestive of frontal lobe dysfunction. This is in keeping with findings of impaired working memory and executive functions in JME (Hommet et al. Neurosci Biobehav Rev.2006;30(1):85-96).The Iowa Gambling Task (IGT) simulates real-life decisions and is a tool to measure impulsive and risky decision-making (Bechara et al. Brain 2000;123:2189-2202).This study investigated impulsivity in JME patients and healthy controls (HC) using the IGT to characterize decision making behaviour. Methods: 21 JME patients and 11 HC, comparable for gender and verbal IQ, were assessed with a computerized version of the IGT. Patients were older than HC (mean age 29 +/- 4(SD) years vs. 35 +/-10). Subjects chose from four decks of cards (A to D) with a total of 100 cards split into five blocks of 20. Deck A and B were indicative of high risk, C and D of low risk behaviour. Advantageous minus disadvantageous choices (C+D-[A+B]) were established for the total number of cards, as well as for each block of 20 cards to analyze changes in risk taking behaviour over time. Results: No difference in the total index of advantageous choices (JME: mean score 14.9 +/- 29.3 (SD); HC: 18.4 +/- 27.0; p=.744) was observed. Both groups learned throughout the task (last versus first block: JME: mean score difference 8.1 +/- 9.2 (SD), p=.001; HC: 10.9 +/- 11.3, p=.009). Post-hoc subgroup analysis revealed that in the seizure free group, the majority of patients improved throughout the task, whereas only half of the patients still experiencing seizures reduced their risk-taking behaviour over time (seizure-free patients: 12 learner/ 2 non-learner vs. 3/ 4; p=.040). Conclusions: This study provides evidence for impaired learning from experience in JME patients who still suffer from seizures. This suggests that inter-ictal network dysfunction might impair the ability to learn, while control of seizures is associated with improved functionality.