Objective To explore the role of default mode network (DMN) in the pathophysiology of depression and the correlations between the functional connectivity (FC) of DMN and the clinical characteristics of depression through the resting-state fMRI scan in depressed patients. Methods Sixteen medication-naïve patients with major depressive disorder and 15 healthy controls were recruited and underwent the resting-state MRI scan. Hamiliton depression rating scale (HAMD) was used to evaluate patients’symptom. The FC of DMN and its correlations with clinical features of pa-tients were analyzed. Results Compared with healthy controls, the FC within DMN in depressed patients is disturbed. There were negative correlations between the left mPFC-left hippocampus FC and HAMD total scores (r=-0.569, P=0.021) and subscale scores for sluggishness (r=-0.498, P=0.050). The left mPFC-right hippocampus FC in patients was negatively correlated with HAMD scores (r=-0.508, P=0.045). There were negative correlations between FC in the hippo-campus and HAMD subscale scores for cognitive impairment (r=-0.509, P=0.044). Conclusions The results suggest that there is abnormal FC within DMN in drug-naïve patients with depression during resting state and some abnormal altera-tions of FC may be correlated with the clinical characteristics in depression.%目的：分析静息态下抑郁症患者默认网络（default mode netwoks，DMN）功能连接的变化，探讨默认网络在抑郁症发病机制中的作用及其与抑郁症临床特征的相关性。方法收集16例抑郁症患者和15名正常对照者完成静息态功能磁共振扫描，比较两组间默认网络内脑区的功能连接强度，采用汉密尔顿抑郁量表（Hamiliton depression rating scale，HAMD）评估患者抑郁症状，分析患者默认网络功能连接与其临床特征的相关性。结果相较于对照组，患者组后扣带回与右侧颞叶、右前额叶、右侧顶叶，左前额叶内侧皮质与右侧扣带回、右侧前额叶，右海马与右前额叶、右侧顶叶，以及左海马与左前额叶、左侧枕叶功能连接增强（P<0.01）；前额叶内侧皮质与左前额叶，右海马与右侧颞叶、左侧边缘叶，左海马与右前额叶（额上回）、右旁中央小叶的功能连接强度下降（P<0.01）。患者组左侧前额叶内侧皮质-左侧海马间的功能连接强度与HAMD总分（r=-0.569，P=0.021）及迟缓因子分（r=-0.498，P=0.050）呈负相关；左侧前额叶内侧皮质-右侧海马功能连接强度与HAMD总分呈负相关（r=-0.508，P=0.045）；两侧海马间的功能连接强度与HAMD认知障碍因子分呈负相关（r=-0.509，P=0.044）。结论静息状态下，未用药抑郁症患者默认网络功能连接存在异常改变，且部分功能连接强度变化与其临床症状存在相关性。
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