Abstracts

Rationale: Cognitive dysfunction is recognized as a common co-morbidity of the idiopathic generalized epilepsies, yet the relationships to other disease variables remain unclear. This study aimed to longitudinally examine cognitive change in patients with juvenile absence epilepsy (JAE) and the relationship to interictal discharge (IEDs) load.


Methods: Twenty patients with JAE undergoing treatment adjustment had comprehensive cognitive assessment and 24-hour ambulatory EEG monitoring at baseline, 6-months and 12-months. JAE was classified with onset of first or predominant absence seizures after age 9 years. Number and change of anti-seizure medications (ASMs) was recorded. Cognition was measured using the comprehensive battery Woodcock Johnson III Test of Cognitive Abilities, with change in cognitive scores assessed using reliable change indices. Epileptiform discharges were quantified from 24-hour recordings, through initial screening with an automated IED detection algorithm and confirmation by two independent reviewers, with adjudication by a third reviewer when discordant. Discharge measures included: 24-hour cumulative ED duration; maximum, mean and median IED duration; cumulative duration and count of IEDs of 3 seconds or longer. The relationship between cognitive performance, IEDs and medication change was explored with mixed effect models.


Results: Mean time between initial assessment to final assessment = 422.54 days, sd = 56.32. Patients with JAE showed a reduced performances in verbal reasoning, memory and learning and processing speed relative to the population mean (Hedge’s g = -0.2 to -0.7, moderate to large effects). The median number of IEDs at initial assessment = 81 (IQR = 837.5) Over 12 months, most patients showed reliable improvement in learning and memory (60%, mean absolute difference = 14.33), though many showed a decline in processing speed (23.08%, mean absolute difference = -2.08). Change in learning and memory over time was associated with ASM adjustment (F = 8.44, p < 0.05), but was not associated with IED load.


Conclusions: Cognitive dysfunction is common in JAE, affecting multiple areas including memory and learning. While adjusting treatment may lead to improvements in these domains for JAE patients, it seems not to be linked to the 24-hour IED burden. Future studies focusing on the distribution of IEDs during sleep could reveal a specific effect on memory encoding, emphasizing its significant role.


Funding: Nil