title: Motor phenotype of decline in cognitive performance among community-dwellers without dementia: population-based study and meta-analysis.
abstract: BACKGROUND
  Decline in cognitive performance is associated with gait deterioration. Our objectives were: 1) to determine, from an original study in older community-dwellers without diagnosis of dementia, which gait parameters, among slower gait speed, higher stride time variability (STV) and Timed Up & Go test (TUG) delta time, were most strongly associated with lower performance in two cognitive domains (i.e., episodic memory and executive function); and 2) to quantitatively synthesize, with a systematic review and meta-analysis, the association between gait performance and cognitive decline (i.e., mild cognitive impairment (MCI) and dementia).
  
  
  METHODS
  Based on a cross-sectional design, 934 older community-dwellers without dementia (mean±standard deviation, 70.3±4.9years; 52.1% female) were recruited. A score at 5 on the Short Mini-Mental State Examination defined low episodic memory performance. Low executive performance was defined by clock-drawing test errors. STV and gait speed were measured using GAITRite system. TUG delta time was calculated as the difference between the times needed to perform and to imagine the TUG. Then, a systematic Medline search was conducted in November 2013 using the Medical Subject Heading terms "Delirium," "Dementia," "Amnestic," "Cognitive disorders" combined with "Gait" OR "Gait disorders, Neurologic" and "Variability."
  
  
  RESULTS
  A total of 294 (31.5%) participants presented decline in cognitive performance. Higher STV, higher TUG delta time, and slower gait speed were associated with decline in episodic memory and executive performances (all P-values <0.001). The highest magnitude of association was found for higher STV (effect size  =  -0.74 [95% Confidence Interval (CI): -1.05;-0.43], among participants combining of decline in episodic memory and in executive performances). Meta-analysis underscored that higher STV represented a gait biomarker in patients with MCI (effect size  =  0.48 [95% CI: 0.30;0.65]) and dementia (effect size  = 1.06 [95% CI: 0.40;1.72]).
  
  
  CONCLUSIONS
  Higher STV appears to be a motor phenotype of cognitive decline.
authors.affiliation: Division of Geriatric Medicine, Department of Neuroscience, Angers University Hospital, Angers, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Beauchet
authors.affiliation: Department of Neurology, Geneva University Hospital and University of Geneva, Geneva, Switzerland.
authors.forename: Gilles
authors.initials: G
authors.lastname: Allali
authors.affiliation: Gait and Brain Lab, Parkwood Hospital, Lawson Health Research Institute, London, Ontario, Canada.
authors.forename: Manuel
authors.initials: M
authors.lastname: Montero-Odasso
authors.affiliation: Department of Electrical and Computer Engineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Ervin
authors.initials: E
authors.lastname: Sejdić
authors.affiliation: Division of Geriatric Medicine, Department of Neuroscience, Angers University Hospital, Angers, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Fantino
authors.affiliation: Division of Geriatric Medicine, Department of Neuroscience, Angers University Hospital, Angers, France; Robarts Research Institute, Department of Medical Biophysics, Schulich School of Medicine and Dentistry, the University of Western Ontario, London, Ontario, Canada.
authors.forename: Cédric
authors.initials: C
authors.lastname: Annweiler
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003072:Cognition Disorders; D060825:Cognitive Dysfunction / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D003704:Dementia; D056344:Executive Function; D005260:Female; D005602:France / Q000453:epidemiology; D005684:Gait; D015577:Geriatric Assessment; D006801:Humans; D008124:Locomotion; D008297:Male; D061212:Memory, Episodic; D010641:Phenotype; D011159:Population Surveillance; D011597:Psychomotor Performance; D036301:Qualitative Research; D012307:Risk Factors