Hippocampal volume reduction was reported to underlie depressive symptomatology, however, the evidence to date remains inconsistent. For the complex intrinsic organization of hippocampus, the hippocampal volumes can be further divided into subfields or axial parts. The current study aimed to explore the alterations of hippocampal sub-regional volumes in first episode drug-naïve major depressive disorder (MDD) by two segmentation methods. Thirty-five first-episode drug-naïve MDD and 35 age- and gender-matched healthy controls (HC) were recruited. Volumes of three sub-regions of hippocampus along the longitudinal axis (head, body and tail) were analyzed manually and eight transverse subfields were automatically determined using FreeSurfer. An asymmetric index (AI) of volumes was defined as (∣Left − Right∣/∣Left + Right∣) * 100. There were significant reductions in the volumes of bilateral hippocampal head in MDD compared to HC. The volumes of eight subfields were not different between groups. MDD patients had higher AI values in the subfield of cornu ammonis 4/dentate gyrus than HC. The change in hippocampal sub-regional volumes might be an imaging biomarker in the first-episode, drug-naïve patients with MDD. Current findings may contribute to developing new diagnostic and therapeutic strategies for major depression.

据报道，海马体积减少是抑郁症状的基础，然而，迄今为止的证据仍然不一致。对于海马复杂的内在组织，海马体积可以进一步分为亚区或轴向部分。目前的研究旨在通过两种分割方法探索首发药物初治重度抑郁症（MDD）海马亚区域体积的变化。招募了 35 名首发药物初治 MDD 和 35 名年龄和性别匹配的健康对照 (HC)。手动分析沿纵轴（头部、身体和尾部）的海马三个子区域的体积，并使用 FreeSurfer 自动确定八个横向子区域。卷的不对称索引 (AI) 定义为 (∣Left − Right∣/∣Left + Right∣) * 100。与 HC 相比，MDD 患者的双侧海马头体积显着减少。八个子域的体积在组间没有差异。MDD患者在羊角4/齿状回亚区的AI值高于HC。海马亚区域体积的变化可能是首发未用药 MDD 患者的影像学生物标志物。目前的发现可能有助于为重度抑郁症开发新的诊断和治疗策略。未接受过药物治疗的 MDD 患者。目前的发现可能有助于为重度抑郁症开发新的诊断和治疗策略。未接受过药物治疗的 MDD 患者。目前的发现可能有助于为重度抑郁症开发新的诊断和治疗策略。