Hippocampal subfield analysis in medication-naïve female patients with major depressive disorder

• Investigation on the hippocampal subfields in medication-naïve female MDD patients.
• We used automated segmentation method of hippocampus.
• Smaller hippocampal subfield volumes in MDD patients compared to healthy controls.
• Illness burden-related parameters could not predict the subfield volumes.

BackgroundHippocampal volume loss is known as the best-replicated finding of structural brain imaging studies on major depressive disorder (MDD). Several evidences suggest localized mechanisms of hippocampal neuroplasticity lead the brain imaging studies on the hippocampus and MDD to perform analyses in the subfield level. The aim of this study was to investigate the differences in total and subfield hippocampal volumes, between medication-naïve female MDD patients and healthy controls, through automated segmentation and volumetric methods.MethodsTwenty medication-naïve female patients diagnosed with MDD and 21 age-matched healthy controls, underwent T1-weighted structural magnetic resonance scanning. Total volumes of both hippocampi and subfield regions were calculated by the automated procedure for volumetric measures implemented in FreeSurfer and automated segmentation method by Van Leemput et al.ResultsWe observed patients to have significantly smaller volumes of the left hippocampus, subiculum, cornu ammonis 2–3, cornu ammonis 4-dentate gyrus, and right subiculum compared to healthy controls. There were no significant predictors for these subfield region volumes among the illness burden-related parameters including duration of illness, number of depressive episodes, severity of depressive symptoms and memory performances.LimitationsOur findings relied on the data of only female participants.ConclusionsWe found significant volume reductions in several hippocampal subfield regions in medication-naïve female MDD patients. Our results are consistent with neurobiological evidences on hippocampal neuroplasticity in MDD, and replicate previous findings that suggest morphologic changes of hippocampal subfields in MDD patients.