Anhedonia is a core feature of major depressive disorder (MDD) and the limbic system has been indicated to be associated with anhedonia in MDD due to its crucial role within the reward circuit. However, the relationship between different regions of the limbic system and MDD, particularly anhedonic symptoms, remains unclear. Therefore, the purpose of this study was to investigate volume changes of various parts of the subcortical limbic (ScLimbic) system in MDD with and without anhedonia. A total of 120 individuals, including 30 MDD patients with anhedonia, 43 MDD patients without anhedonia, and 47 healthy controls (HCs) were enrolled in this study. All subjects underwent structural magnetic resonance imaging scans. After that, ScLimbic system segmentation was performed using the FreeSurfer pipeline ScLimbic. Analysis of covariance (ANCOVA) was performed to identify brain regions with significant volume differences among three groups, and then, post hoc tests were calculated for inter-group comparisons. Finally, correlations between volumes of different parts of the ScLimbic and clinical characteristics in MDD patients were further analyzed. The ANCOVA revealed significant volume differences of the ScLimbic system among three groups in the bilateral fornix (Fx), and the right basal forebrain (BF). As compared with HCs, both groups of MDD patients showed decreased volume in the right Fx, meanwhile, MDD patients with anhedonia further exhibited volume reductions in the left Fx and right BF. However, no significant difference was found between MDD patients with and without anhedonia. No significant association was observed between subregion volumes of the ScLimbic system and clinical features in MDD. The present findings demonstrated that MDD patients with and without anhedonia exhibited segregated brain structural alterations in the ScLimbic system and volume loss of the ScLimbic system might be fairly extensive in MDD patients with anhedonia.

快感缺乏是重度抑郁症 (MDD) 的核心特征，边缘系统由于其在奖赏回路中的关键作用而被认为与 MDD 的快感缺乏相关。然而，边缘系统不同区域与重度抑郁症（特别是快感缺乏症状）之间的关系仍不清楚。因此，本研究的目的是调查有或没有快感缺乏的 MDD 中皮质下边缘 (ScLimbic) 系统各部分的体积变化。本研究共纳入 120 名受试者，其中包括 30 名患有快感缺失的 MDD 患者、43 名无快感缺失的 MDD 患者以及 47 名健康对照者 (HC)。所有受试者均接受结构磁共振成像扫描。之后，使用 FreeSurfer 管道 ScLimbic 进行 ScLimbic 系统分割。进行协方差分析（ANCOVA）来识别三组之间具有显着体积差异的大脑区域，然后计算事后检验以进行组间比较。最后，进一步分析MDD患者ScLmbic不同部分的体积与临床特征之间的相关性。ANCOVA 显示三组 ScLimbic 系统的双侧穹窿 (Fx) 和右侧基底前脑 (BF) 的体积存在显着差异。与HCs相比，两组MDD患者右侧Fx体积均减少，同时，快感缺乏的MDD患者左侧Fx和右侧BF体积进一步减少。然而，有和没有快感缺乏的 MDD 患者之间没有发现显着差异。ScLmbic 系统的分区体积与 MDD 的临床特征之间没有观察到显着的关联。目前的研究结果表明，患有和不患有快感缺乏的 MDD 患者在 ScLimbic 系统中表现出分离的大脑结构改变，并且 ScLimbic 系统的体积损失在患有快感缺乏的 MDD 患者中可能相当广泛。