Fang Zhuo, Lynn Emma, Knott Verner J, Jaworska Natalia
University of Ottawa Institute of Mental Health Research, ON, Canada.
University of Ottawa Institute of Mental Health Research, ON, Canada; Department of Cellular & Molecular Medicine, University of Ottawa, ON, Canada.
Neuroimage Clin. 2025;45:103716. doi: 10.1016/j.nicl.2024.103716. Epub 2024 Nov 26.
The triple network model suggests that dysfunction in three major brain networks - the default mode network (DMN), central executive network (CEN), and salience network (SN) - might contribute to cognitive impairments in various psychiatric disorders, including major depressive disorder (MDD). While hyperconnectivity in the DMN, hypoconnectivity in the CEN, and abnormal SN connectivity have been observed in acutely depressed patients, evidence for network alterations during remission is limited. Further, there are few studies examining connectivity in people in remission from MDD (rMDD) during emotional processing tasks, including during affective cognition (i.e., tasks that encompass affective processing in the context of cognitive processes, such as inhibition). To address these literature gaps, this study compared functional connectivity (FC) between resting and task conditions, specifically during the emotional Stroop (eStroop) task, as well as between rMDD and healthy volunteers (HVs), within and between nodes of the three networks. We also explored how FC relates to rumination in the rMDD group, given that rumination tends to persist in rMDD and involves affective and cognitive networks. We unexpectedly found greater FC during the task vs. rest condition within the DMN, and decreased FC during the task vs. rest conditions within the CEN and SN across the groups. Greater FC during the task vs. rest condition between DMN and SN nodes, as well as between CEN and SN nodes were also observed. These effects were more pronounced in the rMDD group as per our exploratory analyses. Additionally, the rMDD vs. HV group showed higher FC between DMN-CEN nodes, regardless of condition. Higher hopeless rumination scores were associated with decreased resting FC within the DMN, while higher active problem-solving scores were associated with increased task FC within the DMN in the rMDD group. These findings suggest that tasks engaging affective cognition processes influence FC within and among the three networks, with this effect more pronounced in the rMDD group. This might indicate potential protective and compensatory mechanisms in rMDD and expands our understanding of large-scale intrinsic network connectivity alterations during remission from depression. However, given the limited sample and the exploratory nature of some of our analyses, replication is necessary.
三重网络模型表明，三个主要脑网络——默认模式网络（DMN）、中央执行网络（CEN）和突显网络（SN）——功能失调可能导致包括重度抑郁症（MDD）在内的各种精神疾病出现认知障碍。虽然在急性抑郁患者中观察到DMN的超连接性、CEN的低连接性以及SN连接异常，但缓解期网络改变的证据有限。此外，很少有研究考察MDD缓解期患者（rMDD）在情绪处理任务（包括情感认知，即包含在认知过程背景下情感处理的任务，如抑制）中的连接性。为了填补这些文献空白，本研究比较了静息状态与任务状态下的功能连接（FC），特别是在情绪斯特鲁普（eStroop）任务期间，以及rMDD组与健康志愿者（HV）在三个网络节点内部和节点之间的FC。鉴于反刍思维在rMDD中往往持续存在且涉及情感和认知网络，我们还探讨了FC与rMDD组反刍思维的关系。我们意外地发现，在任务状态下DMN内的FC比静息状态下更大，而在任务状态下CEN和SN内的FC比静息状态下降低。在DMN和SN节点之间以及CEN和SN节点之间，任务状态与静息状态相比，FC也更大。根据我们的探索性分析，这些效应在rMDD组中更为明显。此外，无论处于何种状态，rMDD组与HV组相比，DMN - CEN节点之间的FC更高。在rMDD组中，更高的无望反刍分数与DMN内静息FC降低相关，而更高的积极解决问题分数与DMN内任务FC增加相关。这些发现表明，涉及情感认知过程的任务会影响三个网络内部和之间的FC，这种效应在rMDD组中更为明显。这可能表明rMDD中存在潜在的保护和补偿机制，并扩展了我们对抑郁症缓解期大规模内在网络连接改变的理解。然而，鉴于样本量有限以及我们一些分析的探索性性质，有必要进行重复研究。
