title: Role of the Visual and Auditory Systems in Postural Stability in Alzheimer's Disease.
abstract: BACKGROUND
  Postural stability requires the integration of multisensory input information and translation into appropriate motor responses. Surprisingly, few previous studies have addressed the role of auditory input on postural stability in healthy subjects, and none has investigated this in Alzheimer's disease (AD).
  
  
  OBJECTIVE
  To assess the influence of the visual and auditory systems on postural stability in patients with AD and healthy subjects.
  
  
  METHODS
  Twenty-four patients with AD and healthy age-matched subjects were examined by kinematic postural analysis (inertia measurement units placed at the center of mass of the body) under four different conditions: stance with eyes open and eyes closed, with and without suppression of background noise (using ear defenders). The effects of visual and auditory influences were analyzed independently and in conjunction.
  
  
  RESULTS
  In both groups, visual suppression had a negative impact on postural stability, while suppression of background noise, non-specifically and without spatial cues, significantly benefited postural stability. We also observed that in both groups, the positive effect of background noise suppression was insufficient to compensate for the negative effect of visual suppression, to which the patients were significantly more vulnerable.
  
  
  CONCLUSIONS
  Audition, albeit less significant than vision, also plays a role in the multi-sensorial dynamic control of postural stability by the central nervous system. In everyday life, audition is likely to be a relevant factor in postural stability. This is especially relevant in AD in which, even when the peripheral sensory system is intact, the central processing is impaired and sensory dependence is re-weighted.
authors.affiliation: Neurology Department, Centro Hospitalar do Alto Ave, EPE, Guimarães, Portugal.|Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal.|ICVS-3Bs PT Government Associate Laboratory, Braga/Guimarães, Portugal.
authors.forename: Miguel F
authors.initials: MF
authors.lastname: Gago
authors.affiliation: Algoritmi Center, Department of Industrial Electronics, School of Engineering, University of Minho, Braga, Portugal.
authors.forename: Vítor
authors.initials: V
authors.lastname: Fernandes
authors.affiliation: Algoritmi Center, Department of Industrial Electronics, School of Engineering, University of Minho, Braga, Portugal.
authors.forename: Jaime
authors.initials: J
authors.lastname: Ferreira
authors.affiliation: Algoritmi Center, Department of Industrial Electronics, School of Engineering, University of Minho, Braga, Portugal.
authors.forename: Darya
authors.initials: D
authors.lastname: Yelshyna
authors.affiliation: Algoritmi Center, Department of Industrial Electronics, School of Engineering, University of Minho, Braga, Portugal.
authors.forename: Hélder David
authors.initials: HD
authors.lastname: Silva
authors.affiliation: Neurology Department, Centro Hospitalar do Alto Ave, EPE, Guimarães, Portugal.
authors.forename: Maria Lurdes
authors.initials: ML
authors.lastname: Rodrigues
authors.affiliation: Algoritmi Center, Department of Industrial Electronics, School of Engineering, University of Minho, Braga, Portugal.
authors.forename: Luís
authors.initials: L
authors.lastname: Rocha
authors.affiliation: Algoritmi Center, Department of Industrial Electronics, School of Engineering, University of Minho, Braga, Portugal.
authors.forename: Estela
authors.initials: E
authors.lastname: Bicho
authors.affiliation: Neurology Department, Centro Hospitalar do Alto Ave, EPE, Guimarães, Portugal.|Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal.
authors.forename: Nuno
authors.initials: N
authors.lastname: Sousa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000503:physiopathology*; D001307:Auditory Perception; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D004856:Postural Balance; D014796:Visual Perception
keywords: Alzheimer’s disease; auditory system; postural stability; visual system