Association of sleep symptom burden with default mode network homogeneity in first-episode drug-naïve adolescents with major depressive disorder.

BACKGROUND: The default mode network (DMN) plays an important role in depression and sleep regulation. However, whether sleep symptoms are associated with alterations in DMN homogeneity in adolescent major depressive disorder (MDD) remains unclear. This study aimed to investigate whether sleep symptom burden is associated with alterations in DMN homogeneity in adolescents with MDD. METHODS: Following quality control procedures, the final sample comprised 162 first-episode, drug-naïve adolescents with MDD, including 86 participants with higher sleep symptom burden (MDD-S) and 76 participants with lower sleep symptom burden (MDD-NS), together with 53 healthy controls (HCs). Sleep grouping was based on Hamilton Depression Rating Scale (HAMD) sleep items. The DMN was identified using group independent component analysis (ICA). Voxel-wise network homogeneity (NH) values within the DMN were calculated and compared among groups. Correlation analyses and exploratory support vector machine (SVM) analyses were performed. RESULTS: Opposite-direction NH alterations in the precuneus were observed between groups with different sleep symptom burdens. Compared with HCs, the MDD-NS group showed increased NH in the right precuneus, whereas the MDD-S group exhibited decreased NH in the bilateral precuneus. Relative to the MDD-NS group, the MDD-S group showed increased NH in the left anterior cingulate cortex, posterior cingulate cortex, and angular gyrus, together with decreased NH in the right middle temporal gyrus. Exploratory SVM analyses showed modest discriminative performance, indicating limited utility of NH alterations alone for individual-level classification. CONCLUSION: Adolescents with MDD and different levels of sleep symptoms exhibit distinct DMN homogeneity patterns. Sleep symptoms may be associated with altered DMN synchronization patterns, particularly within the precuneus. The opposite-direction precuneus alterations observed across MDD subgroups may provide a potential perspective for understanding some of the heterogeneous DMN findings reported in previous depression studies.