Imagine your brain as a complex network of highways connecting different regions. Well, in patients with first episode, late-life depression (LLD), these highways may be experiencing some traffic jams. A recent study used functional MRI scans and graph theory to investigate the topological properties of brain networks in LLD patients before and after antidepressant treatment. They found that LLD patients had lower clustering coefficients, indicating a decrease in the ability of brain regions to work together efficiently. However, these patients still exhibited a small-world attribute, suggesting some degree of network organization. After 6 months of treatment, depressive symptoms improved, but certain brain regions showed decreased centrality and information transmission efficiency in the cognitive control network. This might be related to progressive cognitive impairment. Overall, this research sheds light on the intricate inner workings of the brain in depression and highlights the potential long-term effects of the condition on cognition. For a deeper dive into the study findings, check out the original research!

ObjectivesTo preliminarily explore the functional activity and information integration of the brains under resting state based on graph theory in patients with first-episode, late-life depression (LLD) before and after antidepressant treatment.MethodsA total of 50 patients with first-episode LLD and 40 non-depressed controls (NCs) were recruited for the present research. Participants underwent the RBANS test, the 17-item Hamilton depression rating scale (HAMD-17) test, and resting-state functional MRI scans (rs-fMRI). The RBANS test consists of 12 sub-tests that contribute to a total score and index scores across the five domains: immediate memory, visuospatial/constructional, language, attention, and delayed memory. Escitalopram or sertraline was adopted for treating depression, and the dosage of the drug was adjusted by the experienced psychiatrists. Of the 50 LLD patients, 27 cases who completed 6-month follow-ups and 27 NCs matched with age, sex, and education level were included for the final statistical analysis.ResultsThere were significant differences in RBANS total score, immediate memory, visuospatial/constructional, language, attention, and delayed memory between LLD baseline group and NCs group (P < 0.05). Considering the global attribute indicators, the clustering coefficient of global indicators was lower in the LLD baseline group than in the NCs group, and the small-world attribute of functional brain networks existed in all three groups. The degree centrality and node efficiency of some brains were lower in the LLD baseline group than in the NCs group. After 6 months of antidepressant therapy, the scores of HAMD-17, immediate memory, language, and delayed memory in the LLD follow-up group were higher than those in the LLD baseline group. Compared with the LLD baseline group, the degree centrality and node efficiency of some brains in the cognitive control network were decreased in the LLD follow-up group.ConclusionsThe ability to integrate and divide labor of functional brain networks declines in LLD patients and linked with the depression severity. After the relief of depressive symptoms, the small-world attribute of functional brain networks in LLD patients persists. However, the information transmission efficiency and centrality of some brain regions continue to decline over time, perhaps related to their progressive cognitive impairment.

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