title: Dual-task complexity affects gait in people with mild cognitive impairment: the interplay between gait variability, dual tasking, and risk of falls.
abstract: OBJECTIVE
  To determine the effect of 2 different dual tasks on gait variability in people with mild cognitive impairment (MCI) compared with control subjects.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Memory clinic at a university hospital.
  
  
  METHODS
  Older adults with MCI (n=43) and cognitively normal control subjects (n=25) from the community. Gait was assessed under single (usual walking) and dual tasking (naming animals and subtracting serial 7s), using an electronic walkway.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  The dependent variable was the coefficient of variation of gait variability, a marker of gait stability and an established risk factor for falls. Two-way repeated-measures analysis of variance was used to examine main effects (group, task) and their interaction.
  
  
  RESULTS
  A significant difference was found within and between groups (P=.016) of increasing gait variability as dual-task complexity increased. Gait velocity decreased within groups as dual-task complexity increased. The magnitude of increased gait variability across tasks was greater for the MCI group (2.68%- 9.84%) than for the control group (1.86%-3.74%), showing a significant between-group difference (P=.041).
  
  
  CONCLUSIONS
  Dual-task load significantly increased gait variability in the MCI group compared with the control group, an effect that was larger than the changes in gait velocity. The magnitude of this impairment on gait stability was related to the complexity of the dual task applied. Our findings help to explain the high risk of falls recently described in older adults with MCI, and may help in the identification of fall risk in cognitively impaired persons.
authors.affiliation: Department of Medicine, Division of Geriatric Medicine, Parkwood Hospital, University of Western Ontario, London, ON, Canada. mmontero@uwo.ca
authors.forename: Manuel
authors.initials: M
authors.lastname: Montero-Odasso
authors.forename: Susan W
authors.initials: SW
authors.lastname: Muir
authors.forename: Mark
authors.initials: M
authors.lastname: Speechley
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control*; D000368:Aged; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D005260:Female; D020233:Gait Disorders, Neurologic / Q000503:physiopathology*; D006801:Humans; D008297:Male; D018570:Risk Assessment; D012720:Severity of Illness Index; D016138:Walking / Q000502:physiology