Structural changes in the hippocampus in major depressive disorder: contributions of disease and treatment.
BACKGROUND
Previous magnetic resonance imaging (MRI) studies of patients with major depressive disorder (MDD) have consistently shown bilateral and unilateral reductions in hippocampal volume relative to healthy controls. Recent structural MRI studies have addressed the question of whether changes in the volume of hippocampal subregions may be associated with MDD.


METHODS
We used a comprehensive and reliable 3-dimensional tracing protocol that enables delineation of hippocampal subregions (head, body, tail) to study changes in the hippocampus of patients with MDD. We recruited 39 MDD patients (16 medicated, 23 unmedicated) and 34 healthy age- and sex-matched controls. We acquired images using a magnetization-prepared rapid acquisition gradient echo sequence on a 1.5-T scanner with a spatial resolution of 1.5 mm x 0.5 mm x 0.5 mm. We performed volumetric analyses, blinded to diagnosis, using the interactive software package Display. All volumes were adjusted for intracranial volume.


RESULTS
We found a significant reduction in the volume of the hippocampal tail bilaterally, right hippocampal head and right total hippocampus in MDD patients. Medicated MDD patients showed increased hippocampal body volume compared with both healthy controls and unmedicated patients.


CONCLUSIONS
This study was cross-sectional. Further prospective studies are needed to determine the direct effect of antidepressant treatment.


CONCLUSIONS
Our results suggest that decreased hippocampal tail and hippocampal head volumes could be trait changes, whereas hippocampal body changes may be dependent on treatment. We showed that long-term antidepressant treatment may affect hippocampal volume in patients with MDD.
Malykhin
Nikolai V
NV
Department of Psychiatry, and Centre for Neuroscience, University of Alberta, Edmonton, Alta. nikolai@ualberta.ca
Carter
Rawle
R
Seres
Peter
P
Coupland
Nicholas J
NJ
D000704:Analysis of Variance; D003430:Cross-Sectional Studies; D003865:Major Depressive Disorder / Q000473:pathology*; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009929:Organ Size; D011795:Surveys and Questionnaires