Anatomical MRI Study of Hippocampus and Amygdala in Patients with Current and Remitted Major Depression

Morphometric MRI studies suggest decreased hippocampal volumes in currently depressed patients, with conflicting findings for the amygdala. We studied these temporal lobe structures and superior temporal gyrus (STG) in patients with current and remitted major depression. We scanned 31 unmedicated depressed patients (21 currently depressed, 10 remitted) and 31 matched healthy controls with a 3D SPGR sequence in a 1.5 Tesla GE Signa Imaging System. There was a trend towards smaller left amygdala volumes in all depressed patients compared with healthy controls. We found significantly smaller hippocampal volumes bilaterally in currently depressed patients than in remitted patients. Furthermore, we found a statistically significant inverse correlation between length of illness and left hippocampus volumes and right superior temporal gyrus volumes. Our finding of smaller hippocampi in currently depressed patients is consistent with the hypothesis that hypercortisolism could result in hippocampal neurotoxicity in major depression. A smaller hippocampal size may be more characteristic of the depressive state and not be present in remitted patients.