Disrupted small-world brain functional network topology in male patients with severe obstructive sleep apnea revealed by resting-state fMRI
Received 23 February 2017
Accepted for publication 19 April 2017
Published 8 June 2017 Volume 2017:13 Pages 1471—1482
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 3
Editor who approved publication: Professor Wai Kwong Tang
Li-Ting Chen,1,* Xiao-Le Fan,2,* Hai-Jun Li,1 Si Nie,1 Hong-Han Gong,1 Wei Zhang,3 Xian-Jun Zeng,1 Ping Long,4 De-Chang Peng1
1Department of Radiology, 2Department of General Surgery, 3Department of Pneumology, 4Department of Otolaryngology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, People’s Republic of China
*These authors contributed equally to this work
Purpose: Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder that can damage cognitive function. However, the functional network organization remains poorly understood. The aim of this study was to investigate the topological properties of OSA patients using a graph theoretical analysis.
Patients and methods: A total of 30 male patients with untreated severe OSA and 25 male education- and age-matched good sleepers (GSs) underwent functional magnetic resonance imaging (MRI) examinations. Clinical and cognitive evaluations were conducted by an experienced psychologist. GRETNA (a toolbox for topological analysis of imaging connectomics) was used to construct the brain functional network and calculate the small-world properties (γ, λ, σ, Eglob, and Eloc). Relationships between these small-world properties and clinical and neuropsychological assessments were investigated in OSA patients.
Results: The networks of both OSA patients and GSs exhibited efficient small-world topology over the sparsity range of 0.05–0.40. Compared with GSs, the OSA group had significantly decreased γ, but significantly increased λ and σ. The OSA group’s brain network showed significantly decreased Eglob (P<0.05) over the sparsity range of 0.09–0.15, but significantly increased Eloc over the sparsity range of 0.23–0.40. In OSA patients, γ was significantly negatively correlated with apnea–hypopnea index (AHI; r=−0.326, P=0.015) and Epworth Sleepiness Scale (ESS; r=−0.274, P=0.043), λ was significantly positively correlated with AHI (r=0.373, P=0.005) and ESS (r=0.269, P=0.047), and σ was significantly negatively correlated with AHI (r=−0.363, P=0.007) and ESS (r=−0.295, P=0.029).
Conclusion: Our results suggest that the high degree of local integration and integrity of the brain connections in OSA patients may be disrupted. The topological alterations of small-world properties may be the mechanism of cognitive impairment in OSA patients. In addition, σ, γ, and λ could be used as a quantitative physiological index for auxiliary clinical diagnoses.
Keywords: obstructive sleep apnea, cognitive impairment, small-world, functional MRI, topological properties
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