Right amygdala lesions are associated with improved mood after epilepsy surgery

Abstract

Neuroimaging studies in healthy and clinical populations strongly associate the amygdala with emotion, especially negative emotions. The consequences of surgical lesions of the amygdala on mood are not well characterized. We tested the hypothesis that amygdala lesions would result in mood improvement. In this study we evaluated a cohort of 52 individuals with medial temporal lobectomy for intractable epilepsy who had resections variably involving the amygdala. All individuals achieved good post-surgical seizure control and had pre- and post-surgery mood assessment with the Beck Depression Inventory (BDI) ratings. We manually segmented the surgical resection cavities and performed multivariate lesion-symptom mapping of change in BDI. Our results showed a significant improvement in average mood ratings from pre- to post-surgery across all patients. In partial support of our hypothesis, resection of the right amygdala was significantly associated with mood improvement (r = 0.5, p = 0.008). The lesion-symptom map also showed that resection of the right hippocampus and parahippocampal gyrus was associated with worsened post-surgical mood. Future studies could evaluate this finding prospectively in larger samples while including other neuropsychological outcome measures.