Disrupted functional brain network organization in patients with obstructive sleep apnea

Abstract

Introduction: Obstructive sleep apnea (OSA) subjects show impaired autonomic, affective, executive, sensorimotor, and cognitive functions. Brain injury in OSA subjects appears in multiple sites regulating these functions, but the integrity of functional networks within the regulatory sites remains unclear. Our aim was to examine the functional interactions and the complex network organization of these interactions across the whole brain in OSA, using regional functional connectivity (FC) and brain network topological properties. Methods: We collected resting-state functional magnetic resonance imaging (MRI) data, using a 3.0-Tesla MRI scanner, from 69 newly diagnosed, treatment-naïve, moderate-to-severe OSA (age, 48.3 ± 9.2 years; body mass index, 31 ± 6.2 kg/m2; apnea-hypopnea index (AHI), 35.6 ± 23.3 events/h) and 82 control subjects (47.6 ± 9.1 years; body mass index, 25.1 ± 3.5 kg/m2). Data were analyzed to examine FC in OSA over controls as interregional correlations and brain network topological properties. Results: Obstructive sleep apnea subjects showed significantly altered FC in the cerebellar, frontal, parietal, temporal, occipital, limbic, and basal ganglia regions (FDR, P < 0.05). Entire functional brain networks in OSA subjects showed significantly less efficient integration, and their regional topological properties of functional integration and specialization characteristics also showed declined trends in areas showing altered FC, an outcome which would interfere with brain network organization (P < 0.05; 10,000 permutations). Brain sites with abnormal topological properties in OSA showed significant relationships with AHI scores. Conclusions: Our findings suggest that the dysfunction extends to resting conditions, and the altered FC and impaired network organization may underlie the impaired responses in autonomic, cognitive, and sensorimotor functions. The outcomes likely result from the prominent structural changes in both axons and nuclear structures, which occur in the condition. This study is aimed to examine resting functional interactions and the complex network organization of these interactions across the whole brain in 69 obstructive sleep apnea (OSA) subjects, relative to 82 control subjects. OSA subjects showed significantly altered functional connectivity in various brain regions regulating autonomic, affective, executive, sensorimotor, and cognitive functions and entire functional brain network in OSA emerged significantly less efficient integration. Previous studies in OSA showed altered functional responses to evoked autonomic, motor, or ventilatory challenges; the findings here suggest that the dysfunction extends to resting conditions, and the altered connectivity and impaired network organization may underlie the impaired responses in cognitive, autonomic, and sensorimotor functions.