Gait Speed and Decline in Gait Speed as Predictors of Incident Dementia.
BACKGROUND
Slow gait is common in dementia, but it remains unknown whether the slowing happens many years prior to dementia onset. We therefore examined the relationship between slow baseline gait speed (GS), change in GS, and the hazard of incident dementia in a community dwelling of elderly people.


METHODS
A total of 3,663 participants dementia-free at baseline (mean age, 73.5 years) were followed up for 9 years from a prospective cohort (Three-City study, France) for incident dementia (all-cause, Alzheimer's disease, vascular dementia, and other causes). GS over 6 m was assessed 4 times over the follow-up using two photoelectric cells. We used a multistate model to estimate the hazard ratio (HR) of dementia for baseline GS and tested a washout period of 4 to 7 years. The role of GS change between 65 and 85 years was examined using linear mixed models and joint models for survival and longitudinal data.


RESULTS
A total of 296 participants developed dementia during the follow-up. In age/sex-adjusted models, 1-SD (0.204 m/s) lower GS was associated with an increased hazard of dementia (HR = 1.59, 95% confidence interval [CI] = 1.39, 1.81, p < .001), with associations evident when gait assessments were taken from 4 years (HR = 1.46; CI = 1.26, 1.68) and 7 years (HR=1.30; CI = 1.00, 1.70) prior to dementia onset. Independently of baseline GS, those with a steeper decline had a higher hazard of dementia (HR per 1 SD [0.007 m/s/year] decrease = 3.39 [1.37-8.43], p = .009).


CONCLUSIONS
Gait is slower up to 7 years prior to clinical onset of dementia. Decline in GS is also more accelerated, suggesting strong links between cognitive and motor function in older adults.
INSERM U942 and Memory Clinical Center, Saint Louis-Lariboisiere-Fernand Widal Hospital, AP-HP, University Paris Diderot, Sorbonne Paris Cité, Paris, France.
Julien
J
Dumurgier
Université Paris-Saclay, Univ. Paris-Sud, UVSQ, CESP, INSERM, Villejuif, France.
Fanny
F
Artaud
INSERM Research Center for Epidemiology and Biostatistics U897, Team Neuroepidemiology, Victor Segalen Bordeaux 2 University, Bordeaux, France.
Célia
C
Touraine
Department of Neurology, University Hospital and Faculty of Medicine, Dijon, France.
Olivier
O
Rouaud
Department of Geriatrics, University Hospital and Faculty of Medicine, Dijon, France.
Béatrice
B
Tavernier
INSERM Research Center for Epidemiology and Biostatistics U897, Team Neuroepidemiology, Victor Segalen Bordeaux 2 University, Bordeaux, France.
Carole
C
Dufouil
Université Paris-Saclay, Univ. Paris-Sud, UVSQ, CESP, INSERM, Villejuif, France.|Department of Epidemiology and Public Health, University College London, UK.
Archana
A
Singh-Manoux
INSERM Research Center for Epidemiology and Biostatistics U897, Team Neuroepidemiology, Victor Segalen Bordeaux 2 University, Bordeaux, France.
Christophe
C
Tzourio
Université Paris-Saclay, Univ. Paris-Sud, UVSQ, CESP, INSERM, Villejuif, France.
Alexis
A
Elbaz
D000368:Aged; D000369:Aged, 80 and over; D003704:Dementia / Q000453:epidemiology / Q000503:physiopathology*; D005260:Female; D020233:Gait Disorders, Neurologic / Q000503:physiopathology*; D015577:Geriatric Assessment; D006801:Humans; D015994:Incidence; D008297:Male; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012307:Risk Factors; D015996:Survival Rate; D000072797:Walking Speed
Alzheimer’s disease; Dementia; Epidemiology; Gait