title: Compensatory Postural Adjustments in an Oculus Virtual Reality Environment and the Risk of Falling in Alzheimer's Disease.
abstract: OBJECTIVE
  Alzheimer's disease (AD) patients have an impaired ability to quickly reweight central sensory dependence in response to unexpected body perturbations. Herein, we aim to study provoked compensatory postural adjustments (CPAs) in a conflicting sensory paradigm with unpredictable visual displacements using virtual reality goggles.
  
  
  METHODS
  We used kinematic time-frequency analyses of two frequency bands: a low-frequency band (LB; 0.3-1.5 Hz; mechanical strategy) and a high-frequency band (HB; 1.5-3.5 Hz; cognitive strategy). We enrolled 19 healthy subjects (controls) and 21 AD patients, divided according to their previous history of falls.
  
  
  RESULTS
  The AD faller group presented higher-power LB CPAs, reflecting their worse inherent postural stability. The AD patients had a time lag in their HB CPA reaction.
  
  
  CONCLUSIONS
  The slower reaction by CPA in AD may be a reflection of different cognitive resources including body schema self-perception, visual motion, depth perception, or a different state of fear and/or anxiety.
authors.affiliation: Neurology Department, Hospital da Senhora da Oliveira, EPE, Guimarães, Braga/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: Centro ALGORITMI, Department of Industrial Electronics, School of Engineering, University of Minho, Braga, Portugal.
authors.forename: Darya
authors.initials: D
authors.lastname: Yelshyna
authors.affiliation: Centro ALGORITMI, Department of Industrial Electronics, School of Engineering, University of Minho, Braga, Portugal.
authors.forename: Estela
authors.initials: E
authors.lastname: Bicho
authors.affiliation: Centro ALGORITMI, Department of Industrial Electronics, School of Engineering, University of Minho, Braga, Portugal.
authors.forename: Hélder David
authors.initials: HD
authors.lastname: Silva
authors.affiliation: Centro ALGORITMI, Department of Industrial Electronics, School of Engineering, University of Minho, Braga, Portugal.
authors.forename: Luís
authors.initials: L
authors.lastname: Rocha
authors.affiliation: Neurology Department, Hospital da Senhora da Oliveira, EPE, Guimarães, Braga/Guimarães, Portugal.
authors.forename: Maria
authors.initials: M
authors.lastname: Lurdes Rodrigues
authors.affiliation: 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: Nuno
authors.initials: N
authors.lastname: Sousa
keywords: Alzheimer's disease; Compensatory postural adjustments; Falls; Inertia measurement units; Oculus virtual reality; Time-frequency distribution