Dynamic functional connectivity differences between insomnia and comorbid insomnia with depression: A neuroimaging...

Previous studies have shown a complex, possibly bidirectional relationship between insomnia disorder (ID) and major depressive disorder (MDD). Neuroimaging evidence suggests the different functional connectivity (FC) of the ID and MDD patients. However, most existing studies rely on static FC analysis, and no direct comparison has been made between ID patients and those with comorbid ID and MDD (IMD). There is rare study to capture the impact of depressive symptoms on the dynamic brain properties of ID patients. To address this gap, the present study used a novel method to calculate the stability of brain dynamic FC (sDFC) based on the sliding window approach. And this method was utilized to compare the dynamic brain properties between ID and IMD patients. Independent samples t-tests identified differences in the sDFC between the ID (n = 47) and IMD (n = 50) groups, and Pearson's correlations examined relationships between sDFC and sleep quality, insomnia symptom severity, and depressive symptoms severity in IMD patients. Results showed increased sDFC in the right supramarginal gyrus and left precuneus in IMD patients, and decreased sDFC in the bilateral putamen, bilateral thalamus, right superior frontal gyrus (SFG), and right middle frontal gyrus. In IMD group, sDFC in the left precuneus was positively correlated with depressive symptoms, while sDFC in the right putamen was negatively correlated with insomnia symptoms, and in the left putamen and right SFG, it was negatively correlated with depressive symptoms. This study is the first to directly compare dynamic brain properties between ID and IMD patients. The result provides a deeper understanding of how co-occurring depression in ID patients affects brain dynamics. The findings highlight potential target brain regions for future neuromodulation interventions, which could enable more effective and personalized treatments for patients with both ID and MDD.