title: Aberrant spontaneous low-frequency brain activity in male patients with severe obstructive sleep apnea revealed by resting-state functional MRI.
abstract: BACKGROUND
  The majority of previous neuroimaging studies have demonstrated both structural and functional abnormalities in obstructive sleep apnea (OSA). However, few studies have focused on the regional intensity of spontaneous fluctuations during the resting state and the relationship between the abnormal properties and the behavioral performances. In the present study, we employed the amplitude of low-frequency fluctuation (ALFF) method to explore the local features of spontaneous brain activity in OSA patients (OSAs).
  
  
  METHODS
  Twenty-five untreated male severe OSAs and 25 age-matched and years-of-education-matched male good sleepers (GSs) were included in this study. The ALFF method was used to assess the local features of spontaneous brain activity. The mean signal values of the altered ALFF areas were analyzed with receiver operating characteristic curve. Partial correlation analysis was used to explore the relationship between the observed mean ALFF values of the different areas and the behavioral performances.
  
  
  RESULTS
  Compared with GSs, OSAs had significantly higher scores for body mass index, apnea-hypopnea index, arterial oxygen saturation <90%, arousal index, and Epworth Sleepiness Scale (ESS) score; furthermore, OSAs had significantly lower scores for rapid eye movement sleep and in the Montreal Cognitive Assessment (MoCA). Compared with GSs, OSAs showed significant lower-ALFF areas in the cluster of the right precuneus and bilateral posterior cingulate gyrus, as well as a higher-ALFF area in the left inferior frontal gyrus. The area under the curve values of the lower- and higher-ALFF areas were 0.90 and 0.93, respectively. Further diagnostic analysis exhibited that the sensibility and specificity of the two clusters were 80% and 92%, respectively. The mean signal value of the lower-ALFF cluster displayed significant positive correlations with lowest oxygen saturation (r=0.447, P=0.025) and MoCA score (r =0.405, P=0.045).
  
  
  CONCLUSIONS
  OSAs may involve in a dysfunction in the default mode network and an adaptive compensatory response in the frontal lobe, which reflect the underlying pathophysiology of cognitive impairment.
authors: Department of Radiology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, People's Republic of China.
authors: Hai-Jun
authors: HJ
authors: Li
authors: Department of Radiology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, People's Republic of China ; Department of Imaging and Interventional Radiology, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong Special Administrative Region, People's Republic of China.
authors: Xi-Jian
authors: XJ
authors: Dai
authors: Department of Radiology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, People's Republic of China.
authors: Hong-Han
authors: HH
authors: Gong
authors: Department of Radiology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, People's Republic of China.
authors: Xiao
authors: X
authors: Nie
authors: Department of Pneumology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, People's Republic of China.
authors: Wei
authors: W
authors: Zhang
authors: Department of Radiology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, People's Republic of China.
authors: De-Chang
authors: DC
authors: Peng
keywords: amplitude of low-frequency fluctuation; blood oxygen-level-dependent; functional magnetic resonance imaging; obstructive sleep apnea; resting state; spontaneous activity
references: Sleep Med. 2012 Jun;13(6):720-7
references: 22503940
references: Am J Respir Crit Care Med. 1997 Dec;156(6):1813-9
references: 9412560
references: Lancet. 2002 Jul 20;360(9328):237-45
references: 12133673
references: Thorax. 2010 Oct;65(10):908-14
references: 20861295
references: Sleep. 2009 Mar;32(3):373-81
references: 19294957
references: J Sleep Res. 2009 Jun;18(2):204-8
references: 19302344
references: Sleep. 1991 Dec;14(6):540-5
references: 1798888
references: Free Radic Biol Med. 2006 May 15;40(10):1683-92
references: 16678006
references: Am Rev Respir Dis. 1993 Sep;148(3):618-21
references: 8368632
references: Sleep. 2003 May 1;26(3):298-307
references: 12749549
references: Proc Am Thorac Soc. 2008 Feb 15;5(2):242-52
references: 18250218
references: Sleep. 2011 Mar 01;34(3):293-301A
references: 21358846
references: J Clin Sleep Med. 2009 Feb 15;5(1):21-7
references: 19317377
references: Neuropsychiatr Dis Treat. 2014 Nov 14;10:2163-75
references: 25484585
references: Brain. 2003 Sep;126(Pt 9):1955-67
references: 12821520
references: Neuroimage. 2006 Jul 15;31(4):1817-25
references: 16626972
references: Am J Respir Crit Care Med. 2002 Nov 15;166(10):1382-7
references: 12421746
references: Sleep. 2007 Nov;30(11):1515-20
references: 18041484
references: Asian Pac J Trop Med. 2012 Nov;5(11):906-10
references: 23146807
references: Am Fam Physician. 1996 Jan;53(1):247-53
references: 8546051
references: Neuroimage. 2010 Jan 15;49(2):1432-45
references: 19782143
references: Brain. 2006 Mar;129(Pt 3):564-83
references: 16399806
references: Thorax. 1989 Dec;44(12):984-9
references: 2694420
references: Neuroimage. 2013 Aug 1;76:183-201
references: 23499792
references: Psychiatry Res. 2005 Dec 30;140(3):211-23
references: 16263248
references: Prog Cardiovasc Dis. 2009 Mar-Apr;51(5):363-70
references: 19249442
references: Proc Natl Acad Sci U S A. 2001 Feb 13;98(4):2029-34
references: 11172070
references: Am J Respir Crit Care Med. 2002 May 1;165(9):1217-39
references: 11991871
references: Proc Natl Acad Sci U S A. 2007 Nov 13;104(46):18265-9
references: 17991778
references: J Neurophysiol. 2002 Sep;88(3):1500-11
references: 12205170
references: Brain. 2003 Jan;126(Pt 1):213-29
references: 12477708
references: Neuropsychiatr Dis Treat. 2012;8:369-73
references: 22977304
references: Sleep. 2008 Jul;31(7):967-77
references: 18652092
references: Sleep. 1992 Apr;15(2):173-84
references: 11032543
references: Chin Med J (Engl). 2009 Jun 20;122(12):1464-8
references: 19567173
references: Stroke. 2006 Sep;37(9):2317-21
references: 16888274
references: Thorax. 2004 Jul;59(7):618-22
references: 15223874
references: Brain Res Bull. 2003 Jun 30;61(1):87-92
references: 12788211
references: Schizophr Res. 2010 Mar;117(1):13-20
references: 19854028
references: Sleep. 2013 May 01;36(5):651-659B
references: 23633747
references: Exp Neurol. 1986 Nov;94(2):247-63
references: 3770117
references: Proc Natl Acad Sci U S A. 2005 Jul 5;102(27):9673-8
references: 15976020
references: Zhongguo Zhen Jiu. 2012 Jan;32(1):47-52
references: 22295826
references: J Appl Physiol (1985). 2003 Mar;94(3):1063-74
references: 12433858
references: Chin Med J (Engl). 2012 Feb;125(4):696-701
references: 22490498
references: Schizophr Res. 2014 Jan;152(1):170-5
references: 24325975
references: Br Med J (Clin Res Ed). 1987 Jan 3;294(6563):16-9
references: 3101779
references: Brain Connect. 2012;2(1):25-32
references: 22432927
references: Proc Natl Acad Sci U S A. 2001 Jan 16;98 (2):676-82
references: 11209064
references: Acta Neurol Scand. 2007 Jan;115(1):1-11
references: 17156260
references: Thorax. 2004 Sep;59(9):804-7
references: 15333860
references: J Sleep Res. 2009 Mar;18(1):36-48
references: 19250174
references: Neuropsychiatr Dis Treat. 2014 Sep 19;10:1819-26
references: 25278755
references: J Neurosci Res. 2012 Oct;90(10 ):2043-52
references: 22715089
references: J Appl Physiol (1985). 2005 Jun;98(6):2226-34
references: 15677733
references: J Clin Sleep Med. 2007 Mar 15;3(2):169-200
references: 17557426
references: Neuroimage. 2011 Jan 15;54(2):787-93
references: 20888921
references: Magn Reson Med. 2000 Sep;44(3):373-8
references: 10975887
references: Am J Respir Crit Care Med. 2001 Mar;163(4):951-7
references: 11282772
references: Brain Dev. 2007 Mar;29(2):83-91
references: 16919409
references: Neuroreport. 2000 Jul 14;11(10):2117-20
references: 10923655
references: Neuroimage. 2007 Apr 1;35(2):488-500
references: 17254803
references: Sleep Med. 2003 Sep;4(5):451-4
references: 14592287
references: Neuroimage. 2013 Jan 1;64:240-56
references: 22926292
references: Sleep. 2010 Feb;33(2):235-41
references: 20175407