Abstracts

Findings of mood-related laterality effects following anterior temporal lobectomy (ATL) have been inconsistent at best. Although previous studies have examined mood at isolated points in time post-surgery, this approach provides little information about intrinsic diurnal variability. In the current study, we explored for the first time whether [quot]variability[quot] in emotional reactivity would be more associated with right versus left ATL and how this variability related to biologic markers of stress (i.e., cortisol). Patients with unilateral ATL (N=16) and age- and education matched controls completed multiple measures of stress and mood, 5 times a day over the course of 5 days. Mood measures included ratings of stress level, affect intensity, and valence using likdert scales. Ratings were made by participants in their home enviroment at predetermined times relative to wakening. They also simultaneously provided spit samples for analysis of salivary cortisol. The right and left ATL groups were matched for age, seizure onset, and time since surgery. All were left language dominant and had nonlesional temporal lobe epilepsy prior to surgery. To index variability in mood, we calculated daily standard deviations for each participant on each measure. These data were analyzed using repeated measures ANOVA[rsquo]s. The Left ATL group showed significantly less variability in their daily ratings of stress, affect intensity, and valence than the Right ATL and Controls. These findings were not due to differential use of antidepressants, the use of medications with mood stabilizing effects (i.e., Depakote), or the occurrence of seizures. The right and left ATL groups did not differ on standard depression or anxiety measures (Beck, STAI). Analysis of corresponding diurnal salivary cortisol levels revealed no significant differences among the groups. All showed the expected pattern of increased cortisol levels upon awakening that progressively decreased over the course of the day. This is the first report that Left ATL patients displayed diurnal mood variability that is more restricted in range than that of Right ATL patients and Controls. This difference in mood variability was not related to scores on traditional mood measures, diurnal patterns of cortisol, patient age, time since surgery, seizure control, or medications. Potential factors underlying this difference will be discussed. Laterality effects may suggest that left temporal lobe systems may play a special role in modulating mood and stress. Analyzing standard deviations of repeated mood measures is a useful and unique way to study emotional changes in epilepsy patients. (Supported by University of Florida Opportunity Fund)