Department of Psychiatry, and National Clinical Research Center for Mental Disorders, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China.
Department of Radiology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China; Clinical Research Center For Medical Imaging in Hunan Province, Changsha, Hunan, China.
J Affect Disord. 2023 Feb 15;323:631-639. doi: 10.1016/j.jad.2022.12.019. Epub 2022 Dec 12.
Late-life depression (LLD) is a common and serious mental disorder, whose neural mechanisms are not yet fully understood. In this study, we aimed to characterize LLD-related changes in intrinsic functional brain networks using a large, multi-site sample.
Using resting-state functional magnetic resonance imaging, the edge-based functional connectivity (FC) as well as multiple topological brain network metrics at both global and nodal levels were compared between 206 LLD patients and 210 normal controls (NCs).
Compared with NCs, the LLD patients had extensive alterations in the intrinsic brain FCs, especially significant decreases in FCs within the default mode network (DMN) and within the somatomotor network (SMN). The LLD patients also showed alterations in several global brain network metrics compared with NCs, including significant decreases in global efficiency, local efficiency, clustering coefficient, and small-worldness, as well as a significantly increased characteristic path length. Moreover, significant alterations in nodal network metrics (increased nodal betweenness and decreased nodal efficiency) were found in patients with LLD, which mainly involved the DMN and SMN. Post-hoc subgroup analyses indicated that the above changes in FC strengths were present in both first-episode, drug-naïve (FEDN) and non-FEDN patients, and were correlated with depression severity in the FEDN patients. Moreover, changes in FC strengths were found in both the early/late-onset (depression starts before/after the age of 50) patients, while altered topological metrics were found in only the late-onset patients.
These results may help to strengthen our understanding of the underlying neural mechanisms and biological heterogeneity in LLD.
老年期抑郁症（LLD）是一种常见且严重的精神障碍，其神经机制尚未完全阐明。在这项研究中，我们旨在使用大型多站点样本描述 LLD 相关的内在功能脑网络变化。
使用静息态功能磁共振成像，比较了 206 例 LLD 患者和 210 例正常对照者（NCs）的边缘功能连接（FC）以及全局和节点水平的多个拓扑脑网络指标。
与 NCs 相比，LLD 患者的内在脑 FC 广泛改变，特别是默认模式网络（DMN）和躯体运动网络（SMN）内的 FC 显著降低。与 NCs 相比，LLD 患者的几个全局脑网络指标也发生了改变，包括全局效率、局部效率、聚类系数和小世界性显著降低，特征路径长度显著增加。此外，还发现 LLD 患者的节点网络指标（节点介数增加和节点效率降低）发生了显著改变，主要涉及 DMN 和 SMN。事后亚组分析表明，FC 强度的上述变化在首次发作、未用药（FEDN）和非 FEDN 患者中均存在，且与 FEDN 患者的抑郁严重程度相关。此外，在早/晚发（抑郁在 50 岁之前/之后开始）患者中均发现 FC 强度变化，而仅在晚发患者中发现拓扑指标改变。
这些结果可能有助于加强我们对 LLD 潜在神经机制和生物学异质性的理解。
