Cognitive function, gait speed decline, and comorbidities: the health, aging and body composition study.
BACKGROUND
Emerging evidence indicates an association between cognitive function and physical performance in late life. This study examines the relationship between cognitive function and subsequent gait speed decline among high-functioning older adults.


METHODS
Measures of global cognitive function (Modified Mini Mental State Examination [3MS]) and executive control function (ECF) (a clock drawing task [CLOX 1] and the 15-item Executive Interview [EXIT 15]) were obtained in the Health, Aging, and Body Composition Study in 1999-2000. Gait-speed (meters/second) was assessed over 20 meters at usual pace. Using a mixed model, we assessed the relationship between baseline cognitive function and gait-speed change over 3 years.


RESULTS
Two thousand, three hundred forty-nine older adults (mean age 75.6 +/- 2.9 years) completed the assessments. After adjustment for baseline gait speed, a 1-standard-deviation (SD) lower performance on each cognitive test was associated with greater gait-speed decline over 3 years: 0.016 m/s for the 3MS (SD = 8.1), 0.009 m/s for CLOX 1 (SD = 2.4), and 0.012 m/s for EXIT 15 (SD = 4.1) (p <.0005 for all). After adjustment for comorbidities, the effect size was attenuated for 3MS and CLOX 1, and the association for EXIT 15 was no longer significant. Depression score was most strongly associated with the EXIT 15 effect reduction.


CONCLUSIONS
Global and executive cognitive functions predict declines in gait speed. The association of ECF with gait speed decline is attenuated by comorbid conditions, particularly depression. Elucidation of the mechanisms underlying these associations may point to new pathways for the treatment of physical decline associated with diminished cognitive function.
Atkinson
Hal H
HH
Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Claude D. Pepper Older Americans Independence Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA. hatkinso@wfubmc.edu
Rosano
Caterina
C
Simonsick
Eleanor M
EM
Williamson
Jeff D
JD
Davis
Cralen
C
Ambrosius
Walter T
WT
Rapp
Stephen R
SR
Cesari
Matteo
M
Newman
Anne B
AB
Harris
Tamara B
TB
Rubin
Susan M
SM
Yaffe
Kristine
K
Satterfield
Suzanne
S
Kritchevsky
Stephen B
SB
D000368:Aged; D000375:Aging / Q000502:physiology*; D001823:Body Composition; D003071:Cognition / Q000502:physiology*; D003863:Depression / Q000503:physiopathology*; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D005684:Gait / Q000502:physiology*; D006304:Health Status; D006801:Humans; D008297:Male; D011379:Prognosis; D011446:Prospective Studies; D016138:Walking / Q000502:physiology*