Abstracts

Rationale: While anterograde memory deficits are well-documented in patients with epilepsy, the extent to which remote memory deficits occur is less clear. This is due in part to a lack of reliable methods for assessment. The present study examined the feasibility of using a novel paradigm, the Transient News Events Test (TNET)¹, to assess remote memory in subjects status-post anterior temporal lobectomy (ATL) for the treatment of refractory seizures. The expectation was to find poorer task performance in the patients with epilepsy compared to a healthy control group. Methods: The TNET was administered to healthy controls and patients with refractory temporal lobe epilepsy (TLE) who had undergone treatment with ATL using the Montreal approach. The test consists of verbally administered recall and recognition questions regarding public events from various domains (e.g. politics, crimes), derived from world almanacs and the New York Times Index. Items appeared briefly in the news, declining in frequency of reporting over the subsequent three years. Events occurred between 1950-1989 in controls and 1950-1994 in subjects with epilepsy. Test items were grouped into 5-year periods (i.e. 1950-1954). The mean recognition and recall TNET scores per hemi-decade were calculated separately for each subject group. Mixed model linear regression was used to test for differences between subject groups, an interaction between subject group and time period tested, and the effect of laterality (right vs. left ATL). Results: Participants included 15 subjects post-ATL and 19 healthy controls (mean ages 41.8 and 41.5 years, respectively). Mean TNET scores are plotted by subject group for each hemi-decade, demonstrating poorer performance in the patient group compared to the controls for recognition (Figure 1) and recall (Figure 2). The observed differences between patients and controls were significant for recognition (p=0.0120) and recall (p=0.0389), adjusted for age, sex and educational level. In addition, there was a significant group by hemi-decade interaction in TNET recognition (p=0.0079) and recall (p=0.0107) scores, adjusted for age, sex and education. The interactions indicated poorer patient performance compared to controls for more recent items (1965-1989), but equivalent performance for more remote items (1950-1964). Data also suggested a trend for those who underwent left ATL to have poorer recognition (p=0.0777) and recall (p=0.0631) when compared to all other subjects. Conclusions: The TNET provides a feasible method for assessment of remote memory function in patients with epilepsy, with decrements in performance noted in comparison to healthy controls. A trend suggested greater long-term memory deficits predicted by left-sided resection. No group differences were evident for the most remote time periods, however, which might suggest that the oldest memories are more resistant to injury. A prospective study using the TNET to assess whether remote memory deficits are caused by ATL will be conducted. ¹J Int Neuropsychol Soc 2000;6:44-51