抑郁症患者大尺度功能脑网络及拓扑属性研究

Study of large-scale functional brain networks and topological properties in patients with major depressive disorder

目的:探讨经过5年随访未发生诊断改变的抑郁症(major depressive disorder,MDD)患者大尺度功能脑网络及网络拓扑属性的改变。方法:2012年1月至2018年8月期间招募住院MDD患者521例,另招募性别、年龄相匹配的健康对照者204例,所有被试完成静息态功能磁共振扫描及临床评估,对招募的MDD患者在其出院≥5年后进行复核诊断,对于未发生诊断改变的258例患者计入抑郁组纳入后续分析。通过构建全脑功能网络,分析两组被试间大尺度脑网络连接差异,在此基础上,进一步分析两组间感觉运动网络(somatomotor networks,SMN)、视觉网络(visual network,VN)及默认网络(default mode network,DMN)拓扑属性差异。采用SPSS 24.0软件进行统计学分析,采用独立样本t检验和χ2检验比较两组数据。结果:与健康对照组相比,MDD组具有显著下降的网络聚类,主要涉及SMN、VN及DMN(单边P<0.001,聚类P<0.05);MDD组在SMN、VN及DMN网络内功能连接(functional connectivity,FC)强度下降,SMN与VN网络间FC强度下降,额顶网络(frontoparietal network,FPN)与DAN网络间FC强度下降(均P<0.05,FDR校正);图论分析显示,MDD组的局部效率、聚类系数及标准化最短路径长度降低,右侧脑岛中部的节点效率、中心度下降及介数下降(均P<0.05,FDR校正)。结论:MDD的网络FC异常,网络拓扑属性破坏,最优化的信息处理能力减弱,网络拓扑属性在一定程度上反映抑郁症状的严重程度,其中脑岛的信息传递能力下降对于网络的功能异常起到了重要作用。

Objective To explore the changes of large-scale functional brain networks and network topological properties in patients with major depressive disorder(MDD)whose diagnosis had not changed after 5 years of follow-up.Methods Totally 521 cases of hospitalized MDD patients were recruited from January 2012 to August 2018,and another 204 cases of gender-and age-matched healthy controls were recruited.All participants completed resting-state functional magnetic resonance scanning and clinical assessment.Their diagnosis were reviewed 5 years after discharge.A total of 258 participants whose diagnosis had not changed were counted into the MDD group for analysis.The differences in large-scale brain network connectivity between the two groups were analyzed by constructing a whole-brain functional network,on the basis of which the altered topological properties of the sensorimotor network(SMN),visual network(VN)and default mode network(DMN)were further analyzed between the two groups.The SPSS 24.0 software was used for data analysis and the independent sample t-test andχ2 test were used for the data comparison of the two groups.Results Compared with the healthy controls,the MDD group had significantly decreased network clustering,mainly involving the SMN,VN and DMN(edge P<0.001,cluster P<0.05).The MDD group had decreased functional connectivity(FC)strength within the SMN,VN and DMN networks,the FC strength between the SMN and VN networks,between the frontoparietal network(FPN)and the DAN networks were decreased(all P<0.05,FDR corrected).Graph-theory analysis showed that local efficiency,clustering coefficient,and normalized shortest path length were decreased in the MDD group,node efficiency was decreased in the left ventral medial prefrontal cortex and the middle of the bilateral insula,node centrality was decreased in the middle of the bilateral insula and occipital lobe,and the betweenness was decreased in the middle of the right insula(all P<0.05,FDR corrected).Conclusion MDD exhibits abnormal network functional connectivity,disruption of network topological properties,diminished optimal information processing,and to some extent reflects the severity of depressive symptoms.The decreased ability of information transfer flow in the insula plays an important role for the functional abnormality of the network.