background Inconsistent results have been reported on structural changes in first episode of major depressive disorder. The studies mainly focused on hippocampus and amygdala volume. Here, it remains unclear whether hippocampal volume is already affected early in the course of depression since a decrease in its volume has clearly been associated with the recurrence of the disease. Secondly, it is unclear whether amygdala volume is enlarged early in the course of the disease and in how far that is state -related. Finally a recent study investigating the cortical thickness in depressed patients suggest that this may already be altered as a trait factor of the disease.
aim To investigate possible changes of subcortical structures as well as cortical thickness taking possible state- and trait-related changes early in the course of depression into account.
methods 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 as well as semi-automatic measurement of cortical thickness were performed.
results Manual volumetry revealed larger amygdala volumes bilaterally in patients with a current first episode in comparison with remitted patients and healthy controls. Compared to controls, cortical thickness in higher order visual areas was reduced in acutely depressed and increased in recovered patients in regions involved in emotion regulation.
conclusion With respect to subcortical structures, our study provides further evidence for state-dependant amygdala enlargement already during but not in remission from the first episode of major depressive disorder in the absence of any hippocampal changes. Moreover, our results provide first evidence that early in the course of depression region-specific cortical thickness may show plastic changes.