Bidirectional structural-functional connectivity coupling reorganization in obstructive sleep apnea.

BACKGROUND

Obstructive sleep apnea (OSA) is associated with widespread cognitive and neural dysfunction; however, how chronic intermittent hypoxia and sleep fragmentation reshape the relationship between structural and functional brain connectivity remains unclear. Structural-functional connectivity (SC-FC) coupling provides a multimodal framework for characterizing the correspondence between anatomical architecture and functional communication.

METHODS

Fifty patients with moderate-to-severe OSA and fifty matched healthy controls (HCs) underwent overnight polysomnography and multimodal MRI scanning, including resting-state functional MRI and diffusion tensor imaging. Regional SC-FC coupling was calculated using SC and FC matrices derived from the Brainnetome Atlas. Group differences in regional SC-FC coupling were examined across 246 regions, and exploratory correlation analyses were performed with cognitive and clinical measures.

RESULTS

Compared with HCs, patients with OSA showed significantly increased SC-FC coupling in frontal-insular, posterior default-mode, sensorimotor, and visual regions. In contrast, significantly decreased SC-FC coupling was observed in temporal-associative, limbic, and subcortical regions. Increased SC-FC coupling in the superior frontal gyrus, precuneus, and insula was associated with poorer psychomotor vigilance performance, including prolonged reaction times and increased lapse frequency. Reduced hippocampal and subcortical coupling was associated with nocturnal hypoxia burden, including increased percentage of sleep time spent below 90% oxygen saturation and lower minimum oxygen saturation. Inferior parietal lobule coupling showed a weaker association with apnea-hypopnea index severity.

CONCLUSION

OSA is associated with bidirectional regional SC-FC coupling reorganization, characterized by hypercoupling in attention-related systems and hypocoupling in limbic-subcortical regions. These exploratory findings suggest that distinct coupling patterns may relate to different clinical dimensions of OSA, including vigilance impairment and nocturnal hypoxic burden.