DeFREE Research Cluster, Department of Psychology, University of Southern Denmark, Odense, Denmark.
Department of Public Health, University of Southern Denmark, Odense, Denmark.
J Psychiatr Res. 2024 Sep;177:412-419. doi: 10.1016/j.jpsychires.2024.07.037. Epub 2024 Jul 30.
Monozygotic twins share the same genotype; however, they can be phenotypically discordant on various traits. Studying discordant monozygotic twins allows the investigation of differences in associations between symptoms and psychopathological risk factors, controlled for shared genetic liability. The network approach to psychopathology suggests that depressive symptoms, along with risk and protective factors (e.g., cognition, daily activities), form a complex system of mutually interacting components. We compared monozygotic twins discordant for lifetime depression on their respective extended networks of depressive symptoms, cognitive functions and daily activities (intellectual, physical, social), and evaluated if these networks differ in their associations between variables and in the role of each variable within the network. Regularized partial correlations investigated the networks' composition in 147 monozygotic twin pairs discordant for depression from the Danish Twin Registry. Affected twins had stronger overall associations within their network of depressive symptoms, cognitive functions and daily activities than their unaffected co-twins, while the importance of the network components' associations did not differ between the co-twins. In affected twins, decreased frequency in experiencing happiness had the strongest association with remaining variables (i.e., the most influence in activating other network elements). Also, variables from different groups were significantly associated (e.g., loneliness with delayed memory, pessimism with low social activities, verbal learning with intellectual activities). In unaffected twins, both mood symptoms and cognitive functions were important, but between-groups associations were quasi-absent. These results suggest that external events affecting the ability to feel happiness likely trigger the psychopathological process (depression network activation), independently from the genetic predisposition to depression.
同卵双胞胎具有相同的基因型；然而，他们在各种特征上可能表现出不同的表型。研究不同表型的同卵双胞胎可以研究症状和精神病理风险因素之间的关联差异，同时控制共同的遗传易感性。精神病理学的网络方法表明，抑郁症状以及风险和保护因素（例如认知、日常活动）形成了一个相互作用的复杂系统。我们比较了一生中患有抑郁症的同卵双胞胎在各自的抑郁症状、认知功能和日常活动（智力、身体、社会）的扩展网络上的差异，并评估这些网络在变量之间的关联以及每个变量在网络中的作用是否不同。在丹麦双胞胎登记处中，对 147 对患有抑郁症的同卵双胞胎进行了正则化偏相关分析，以研究这些网络的组成。受影响的双胞胎在其抑郁症状、认知功能和日常活动网络中的整体关联比未受影响的同卵双胞胎更强，而网络中各变量的关联重要性在同卵双胞胎之间没有差异。在受影响的双胞胎中，幸福感降低与其余变量的关联最强（即对激活其他网络元素的影响最大）。此外，不同组的变量也存在显著关联（例如，孤独与记忆延迟、悲观与社交活动减少、词汇学习与智力活动）。在未受影响的双胞胎中，情绪症状和认知功能都很重要，但组间关联几乎不存在。这些结果表明，影响幸福感的外部事件可能会独立于抑郁的遗传易感性，触发精神病理过程（抑郁网络激活）。
