Amygdala enlargement in dysthymia—a volumetric study of patients with temporal lobe epilepsy

Background: Previous studies indicated an important role of the amygdala for emotional information processing. We investigated a possible relationship between amygdala volumes, aggressive behavior, and dysthymia, in patients with temporal lobe epilepsy (TLE). Methods: Patients with TLE with and without aggression or dysthymia and healthy volunteers were assessed using quantitative MRI. Amygdala volumes were measured in a blinded fashion and corrected for total brain volumes. Results: There was a highly significant enlargement of left and right amygdala volumes in patients with dysthymia (right side, p< .000; left side, p = .001). We found a significant positive correlation between left amygdala volumes (p = .02) and a trend towards positive correlation between right amygdala volumes and depression (p = .06), as measured with the Beck Depression Inventory. Amygdala volumes of females were significantly larger than those of males (left side: p = .005; right side: p = .06). Conclusions: This is the second report of a relationship between amygdala volumes and depressed mood, confirming an earlier finding in patients with bipolar disease, and the first study reporting a correlation between amygdala volumes and depression. Increased processing of emotional information might increase amygdala blood flow and subsequently, result in amygdala enlargement.