Abstracts

Rationale: Development of episodic memory in childhood follows a curvilinear trajectory with rapid progression until 9 years of age and reaches a plateau after 11 years of age. The progression between ages 9 and 12 has been attributed to developmental changes in strategy utilization associated with maturation of the frontal lobes. The Rey Auditory-Verbal Learning Test (AVLT) is a measure of episodic memory and strategy utilization, and Snyder et al (2005) found improved learning/recall and no adverse effects of surgery on the development of strategy utilization for children with various focal epilepsies. The specific effects of temporal lobe epilepsy on strategy utilization were evaluated and compared to utilization in children without epilepsy to further understand this development.Methods: AVLT performance of 22 persons (11 with TLE), initially assessed as preadolescents and again as adolescents, was scored for frequency of word pairs (PF) on four blocks of successive trials (a measure of subjective organization) and for serial positions for Trial 1 and across trials (a measure of sequential organization). Mean ages at time of assessment were 9.3 and 15.3 years and the mean Full Scale IQ was 90. There were no significant differences in age, IQ, or gender ratio for persons with and without epilepsy.Results: Repeated measures analysis of variance (ANOVA) were computed on frequency of paired words (PF ) for four successive learning blocks and on serial positions (initial, middle, final) for trial 1 and all trials combined. There was a significant difference of age for the fourth learning block (.017), and for all serial position effects (p≤.01) for combined trials and for initial words in trial 1 (.001). These differences were found for persons with and without epilepsy. The increase in subjective organization between childhood and adolescence was specific to later AVLT trials and for all serial positions regardless of diagnostic category. Total AVLT learning and recall also increased with age (.0001) as expected.Conclusions: Relative to their performance as children, adolescents with temporal lobe epilepsy showed greater use of organizational strategies and improvement in verbal learning and recall of unrelated words, as did adolescents without epilepsy. Improved learning/recall was not due to changes in working memory. Rather, results support a discontinuity in the development of memory based on increased efficiency of encoding and transfer to long-term memory as a consequence of active, effortful use of organizational strategies associated with prefrontal maturation. Temporal lobe epilepsy did not appear to have significant negative effect on this developmental change.