Abstracts

Rationale: Individuals with pharmacoresistant temporal lobe epilepsy (TLE) often experience progressive decline in memory and other cognitive functions (Kent et al., 2006). Previous work has shown that patients with epileptic seizures perform more poorly on many neuropsychological tests than normal individuals (Klove & Matthews, 2003; Oyegbile et al., 2004). While multiple cognitive functions remain compromised, the most prominent cognitive deficit associated with uncontrolled seizures in patients with TLE is memory impairment (Hermann & Seidenberg, 2002; Schomer et al., 2002). This is expected since neuropsychological studies demonstrate that mesial temporal lobe structures are essential for memory functioning (Helmstaedter, Sonntag-Dillender, Hoppe, & Elger, 2004).While substantial research has demonstrated memory impairment in TLE patients, little work has examined whether emotional stress contributes to this memory impairment. Although few would argue that there is a relationship between stress and epilepsy, the nature of that relationship remains to be fully understood. Research does indicate that individuals with TLE have a higher incidence of emotional distress, particularly anxiety and depression, than the general population (Reuber et al., 2004). Yet the potential contribution of this stress to memory dysfunction in TLE has not been examined. That was the purpose of the present study. Methods: Participants: Diagnosis of TLE for all participants (n = 124) was confirmed by prolonged video/EEG monitoring (PVEM) in addition to concordance of imaging findings such as MRI, PET, and ictal SPECT. Procedure: Two indices of stress were used in the study: (1) A combination of Scales 2 (Depression) and 7 (Psychasthenia) from the MMPI-2; and, (2) seizure frequency. Data Analyses: Factor analysis was chosen to identify the factor structure of the memory measures selected and to assist in reducing the number of memory measures into a more parsimonious factor composite. Multiple linear regression was used to examine the association between degree of emotional stress and memory impairment on measures of verbal and nonverbal material. Results: The results of the factor analysis revealed two factors which were retained for subsequent data analyses. One factor was a composite of all verbal memory measures. The second factor was comprised of a single test of nonverbal memory. Results support the hypothesis that higher levels of emotional distress are associated with memory impairment, particularly with regard to verbal memory functioning in TLE. Self-reported seizure frequency was not associated with either verbal or nonverbal memory impairment, nor was it related to the MMPI index of emotional distress. Conclusions: The results suggest that emotional distress contributes to memory impairment in patients with TLE. These findings have implications for understanding the role of stress in memory functioning in patients with pharmacoresistant TLE. They also suggest the possibility that stress reduction interventions may have a beneficial effect on memory functioning in this group of individuals.