title: Sleep EEG Characteristics in Young and Elderly Patients with Obstructive Sleep Apnea Syndrome.
abstract: OBJECTIVE
  In the present study, it was hypothesized that the sleep electroencephalogram (EEG) characteristics of young (<30 yrs) and elderly (>55 yrs) OSAS patients would differ.
  
  
  METHODS
  We analyzed 76 sleep EEG recordings from OSAS patients (young group: n=40, mean age: 24.3±4.9 yrs; elderly group: n=36, mean age: 59.1±4.9 yrs), which were obtained during nocturnal polysomnography. The recordings were assessed via spectral analysis in the delta (0.5-4.5 Hz), theta (4.5-8 Hz), alpha (8-12 Hz), beta (12-32 Hz), slow sigma (11-13 Hz), and fast sigma (13-17 Hz) frequency bands.
  
  
  RESULTS
  Apnea Hypopnea Index (AHI) and sleep efficiency (%) did not differ significantly between the two groups (19.8±14.4 vs. 25.9±16.0, p=0.085; 84.4±12.6 vs. 80.9±11.0, p=0.198, respectively). After adjusting for gender, the slow/fast sigma ratio was not significantly correlated with AHI in the elderly group (r=-0.047, p=0.790) but AHI was inversely correlated with the slow/fast sigma ratio in the young group (r=-0.423, p=0.007). A multiple linear regression analysis revealed that a higher AHI was related with a lower slow/fast sigma ratio in the young group (β=-0.392, p=0.028) but not the elderly.
  
  
  CONCLUSIONS
  In the present study, sleep EEG activity differed between young and elderly OSAS patients. The slow/fast sigma ratio was associated with OSAS severity only in young patients, suggesting that young OSAS patients may have a distinctive brain plasticity compared with elderly patients.
authors.affiliation: Department of Psychiatry and Center for Sleep and Chronobiology, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Yu Jin
authors.initials: YJ
authors.lastname: Lee
authors.affiliation: NHMRC Centre for Integrated Research and Understanding of Sleep, Woolcock Institute of Medical Research, The University of Sydney, Sydney, Australia.; School of Physics, The University of Sydney, Sydney, Australia.
authors.forename: Jong Won
authors.initials: JW
authors.lastname: Kim
authors.affiliation: Department of Psychiatry, Seoul Metropolitan Eunpyeong Hospital, Seoul, Republic of Korea.
authors.forename: Yu-Jin G
authors.initials: YJ
authors.lastname: Lee
authors.affiliation: Department of Psychiatry and Center for Sleep and Chronobiology, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Do-Un
authors.initials: DU
authors.lastname: Jeong
keywords: OSAS; Sleep EEG; Sleep spindle