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.