Imagine driving down a road with unexpected potholes and speed bumps, that’s what obstructive sleep apnea (OSA) patients with mild cognitive impairment experience in their brains. A recent study used functional magnetic resonance imaging (fMRI) to investigate the dynamic functional network connectivity (FNC) in male OSA patients, comparing those with normal cognition (OSA-NC) to those with mild cognitive impairment (OSA-MCI). The results revealed two distinct connectivity states: one with stronger and slower connectivity (State I) and one with weaker and faster connectivity (State II). OSA-MCI patients spent more time in State I, indicating abnormal FNC properties. Interestingly, the number of transitions between the states was linked to cognitive impairment in OSA-MCI patients. The study also identified abnormal functional connectivity in key brain networks involved in salience, default mode, and executive control. These findings shed light on the underlying neural mechanisms of OSA and its impact on cognitive function.

ObjectiveThe purpose of this study was to investigate the dynamic functional network connectivity (FNC) and its relationship with cognitive function in obstructive sleep apnea (OSA) patients from normal cognition (OSA-NC) to mild cognitive impairment (OSA-MCI).Materials and methodsEighty-two male OSA patients and 48 male healthy controls (HC) were included in this study. OSA patients were classified to OSA-MCI (n = 41) and OSA-NC (n = 41) based on cognitive assessments. The independent component analysis was used to determine resting-state functional networks. Then, a sliding-window approach was used to construct the dynamic FNC, and differences in temporal properties of dynamic FNC and functional connectivity strength were compared between OSA patients and the HC. Furthermore, the relationship between temporal properties and clinical assessments were analyzed in OSA patients.ResultsTwo different connectivity states were identified, namely, State I with stronger connectivity and lower frequency, and State II with lower connectivity and relatively higher frequency. Compared to HC, OSA patients had a longer mean dwell time and higher fractional window in stronger connectivity State I, and opposite result were found in State II, which was mainly reflected in OSA-MCI patients. The number of transitions was an increasing trend and positively correlated with cognitive assessment in OSA-MCI patients. Compared with HC, OSA patients showed extensive abnormal functional connectivity in stronger connected State I and less reduced functional connectivity in lower connected State II, which were mainly located in the salience network, default mode network, and executive control network.ConclusionOur study found that OSA patients showed abnormal dynamic FNC properties, which was a continuous trend from HC, and OSA-NC to OSA-MCI, and OSA patients showed abnormal dynamic functional connectivity strength. The number of transformations was associated with cognitive impairment in OSA-MCI patients, which may provide new insights into the neural mechanisms in OSA patients.

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