background Inconsistent results have been reported on structural changes in first episode of major depressive disorder. Studies have consistently reported lower hippocampal volumes in recurrent depression, and some have found lower hippocampal volumes in first episodes of depression. Three studies reported larger amygdala volumes in first episode patients, but these studies were possibly confounded by the current use of medication.

method Twenty medication-naive patients with first episode dsm-iv major depressive disorder, twenty patients with first major depressive episode in remission, currently without medication and 20 healthy controls were assessed by use of structural magnetic resonance imaging. Groups were matched for sex, age and education. Manual volumetry of hippocampal and amygdala volumes and voxel based morphometry (vbm) were performed.

results No significant changes in vbm were observed. Manual volumetry revealed larger amygdala volumes bilaterally in patients with a current first episode in comparison with remitted patients and healthy controls.

conclusion Our study provides further evidence for state-dependant amygdala enlargement already during but not in remission from the first episode of major depressive disorder. These changes were found in a medication naive sample, hereby controlling for confounding effects of medication.