Abnormal resting-state functional connectivity within the default mode network subregions in male patients with obstructive sleep apnea

Neuropsychiatric Disease and Treatment Dovepress open access to scientific and medical research Original Research Neuropsychiatric Disease and Treatment downloaded from https://www.dovepress.com/ by 54.37.117.73 on 12-Jul-2018 For personal use only. Open Access Full Text Article Abnormal resting-state functional connectivity within the default mode network subregions in male patients with obstructive sleep apnea This article was published in the following Dove Press journal: Neuropsychiatric Disease and Treatment 19 January 2016 Number of times this article has been viewed Hai-Jun Li 1 Xiao Nie 1 Hong-Han Gong 1 Wei Zhang 2 Si Nie 1 De-Chang Peng 1 Department of Radiology, Department of Pneumology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province, People’s Republic of China 1 2 Background and objective: Abnormal resting-state functional connectivity (rs-FC) between the central executive network and the default mode network (DMN) in patients with obstructive sleep apnea (OSA) has been reported. However, the effect of OSA on rs-FC within the DMN subregions remains uncertain. This study was designed to investigate whether the rs-FC within the DMN subregions was disrupted and determine its relationship with clinical symptoms in patients with OSA. Methods: Forty male patients newly diagnosed with severe OSA and 40 male education- and age-matched good sleepers (GSs) underwent functional magnetic resonance imaging (fMRI) examinations and clinical and neuropsychologic assessments. Seed-based region of interest rs-FC method was used to analyze the connectivity between each pair of subregions within the DMN, including the medial prefrontal cortex (MPFC), posterior cingulate cortex (PCC), hippocampus formation (HF), inferior parietal cortices (IPC), and medial temporal lobe (MTL). The abnormal rs-FC strength within the DMN subregions was correlated with clinical and neuropsychologic assessments using Pearson correlation analysis in patients with OSA. Results: Compared with GSs, patients with OSA had significantly decreased rs-FC between the right HF and the PCC, MPFC, and left MTL. However, patients with OSA had significantly increased rs-FC between the MPFC and left and right IPC, and between the left IPC and right IPC. The rs-FC between the right HF and left MTL was positively correlated with rapid eye movement (r=0.335, P=0.035). The rs-FC between the PCC and right HF was negatively correlated with delayed memory (r=-0.338, P=0.033). Conclusion: OSA selectively impairs the rs-FC between right HF and PCC, MPFC, and left MTL within the DMN subregions, and provides an imaging indicator for assessment of cognitive dysfunction in OSA patients. Keywords: obstructive sleep apnea, functional connectivity, default mode network, functional MRI, cognitive impairment Introduction Correspondence: De-Chang Peng Department of Radiology, The First Affiliated Hospital of Nanchang University, No 17, Yongwai Zheng Street, Donghu District, Nanchang 330006, Jiangxi Province, People’s Republic of China Tel +86 791 8869 4457 Email 203 submit your manuscript | www.dovepress.com Neuropsychiatric Disease and Treatment 2016:12 203–212 Dovepress © 2016 Li et al. This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License (http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms (https://www.dovepress.com/terms.php). http://dx.doi.org/10.2147/NDT.S97449 Powered by TCPDF (www.tcpdf.org) Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder caused by repeated complete or partial collapse of the upper airway during sleep, resulting in intermittent hypoxia (IH), intermittent hypercapnia, and sleep fragmentation.1 Based on the results of populations studies, it has been found that OSA affects approximately 5.7%–6.0% of middle-aged men and 2.4%–4.0% of middle-aged women.2,3 OSA has been shown to increase daytime sleepiness, road traffic accidents, stroke, hypertension, coronary artery disease, congestive heart failure, insulin resistance, and cardiovascular mortality.4–8 The common cognitive impairments, including impaired memory, learning, and attention have been commonly observed in patients with OSA, because Dovepress Neuropsychiatric Disease and Treatment downloaded from https://www.dovepress.com/ by 54.37.117.73 on 12-Jul-2018 For personal use only. Li et al of both sleep disturbances and hypoxemia.9,10 However, the underlying neural mechanisms remain unclear. Structural and functional neuroimaging techniques have evolved and have been used to increase our understanding of neurocognitive processes and structural brain differences. Previous voxel-based morphometry (VBM) studies have reported conflicting results in patients with OSA,11–18 and failed to fully explain the differences in the pathophysiology or severity of disease. For example, one study failed to identify any regions of gray matter (GM) reduction.14 Another study showed widespread loss of more than 20 foci of GM concentration.17 Impaired hippocampus was a relatively consistent finding across different neuroimaging techniques in previous studies.12,13,16,17,19 The hippocampus region is closely associated with neural processing of memory.20 Prilipko et al21 found that patients with OSA had a significant inactivation in the medial temporal regions within the default mode network (DMN) and a significant activation in the right ventral frontoparietal network during the tasks. In addition, Sweet et al22 found a deactivation in the posterior cingulate and right postcentral gyrus within the DMN during continuous positive airway pressure (CPAP) withdrawal during working memory tasks using functional magnetic resonance imaging (fMRI) in patients with OSA. Magnetic resonance spectroscopy is a useful neuroimaging tool to measure changes in either the concentration or distribution of chemical substances. Bartlett et al23 found an elevated N-acetylaspartate (NAA)-to-creatine (Cr) ratio (NAA/Cr) and lowered Cr levels in the left hippocampus area, which were associated with neurocognitive performance and OSA severity. O’Donoghue et al24 found a decreased frontal NAA-to-choline (Cho) ratio (NAA/Cho) and hippocampus Cho/Cr ratio in patients with OSA, which persisted after CPAP treatment. However, in the recent years, resting-state fMRI (rs-fMRI)-based functional connectivity (FC) has been widely used for objective analysis of the brain’s functional connectome.25,26 Resting-state FC-based region of interest (ROI) has been regar (...truncated)