title: Sleep-related breathing disorders and gait variability: a cross-sectional preliminary study.
abstract: BACKGROUND
  Sleep-related breathing disorders (SRBDs) provoke cognitive and structural brain disorders. Because these disorders have been associated with unsafe gait characterized by an increase in stride-to-stride variability of stride time (STV), we hypothesised that SRBDs could be associated with an increased STV. The aim of this study was to examine the association between SRBDs and STV in French healthy older community-dwellers.
  
  
  METHODS
  A total of 49 participants (mean age 69.6 ± 0.8 years; 65.2% female) were included in this cross-sectional study. All participants, who were free of clinically diagnosed SRBDs before their inclusion, had a nocturnal unattended home-sleep assessment. There were separated in three group based on apnea + hypopnea index (AHI): AHI <15 defining the absence of SRBD, AHI between 15-30 defining mild SRBD, and AHI >30 defining moderate-to-severe SRBD. Coefficient of variation of stride time, which is a measure of STV, was recorded while usual walking using SMTEC® footswitches system. Digit span score was used as a measure of executive performance. Age, gender, body mass index (BMI), number of drugs daily taken, vision, proprioception, history of falls, depression symptoms, global cognitive functioning were also recorded.
  
  
  RESULTS
  STV and BMI were higher in participants with mild SRBDs (P = 0.031 and P = 0.020) and moderate-to-severe SRBDs (P = 0.004 and P = 0.002) compared to non-SRBDs. STV positively correlated with AHI (P = 0.036). Lower (i.e., better) STV was associated with the absence of SRBDs (P = 0.021), while greater (i.e., worse) STV was associated with moderate-to-severe SRBD (P < 0.045) but not with mild SRBD (P > 0.06).
  
  
  CONCLUSIONS
  Our results show a positive association between STV and SRBDs, with moderate-to-severe SRBD being associated with greater gait variability. This association opens new perspectives for understanding gait disorders in older adults with SRBDs and opens the door to treatments options since SRBDs are potential treatable factors.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Celle
authors.forename: Cédric
authors.initials: C
authors.lastname: Annweiler
authors.forename: Richard
authors.initials: R
authors.lastname: Camicioli
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Barthélémy
authors.forename: Frédéric
authors.initials: F
authors.lastname: Roche
authors.affiliation: Department of Neuroscience, Division of Geriatric Medicine, UPRES EA 4638, UNAM, Angers University Hospital, 49933 Angers, Cedex 9, France. OlBeauchet@chu-angers.fr.
authors.forename: Olivier
authors.initials: O
authors.lastname: Beauchet
mesh_terms: D000368:Aged; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D056344:Executive Function; D005260:Female; D005602:France; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D017286:Polysomnography; D012720:Severity of Illness Index; D012891:Sleep Apnea Syndromes / Q000503:physiopathology* / Q000523:psychology; D016138:Walking / Q000502:physiology