Structural and functional neuroimaging correlates of depression in temporal lobe epilepsy

Depression is commonly experienced among persons with temporal lobe epilepsy (TLE). Although evidence exists implicating dysfunction of distributed neural structure and circuitry among depressed persons without epilepsy, little is known regarding the neural correlates of depression in TLE. We examined the relationship between self-reported depression severity and both structural MRI volumetry and [(18)F]fluorodeoxyglucose positron emission tomography (PET)-measured resting metabolism of the amygdala and hippocampus of 18 patients with TLE. Significant positive relationships were noted between right and left amygdala volumes and depression. No other significant relationships were observed between amygdala PET measures, hippocampal volumes, or hippocampal PET measures and degree of depressive symptomatology. These findings indicate that both right and left amygdala volumes are associated with depression severity among persons with TLE. Future studies examining the potential role of extended neural regions may clarify the observed structural relationship between depressive symptoms and the amygdala.