title: Cognitive function, gait speed decline, and comorbidities: the health, aging and body composition study.
abstract: 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.
authors: 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
authors: Hal H
authors: HH
authors: Atkinson
authors: Caterina
authors: C
authors: Rosano
authors: Eleanor M
authors: EM
authors: Simonsick
authors: Jeff D
authors: JD
authors: Williamson
authors: Cralen
authors: C
authors: Davis
authors: Walter T
authors: WT
authors: Ambrosius
authors: Stephen R
authors: SR
authors: Rapp
authors: Matteo
authors: M
authors: Cesari
authors: Anne B
authors: AB
authors: Newman
authors: Tamara B
authors: TB
authors: Harris
authors: Susan M
authors: SM
authors: Rubin
authors: Kristine
authors: K
authors: Yaffe
authors: Suzanne
authors: S
authors: Satterfield
authors: Stephen B
authors: SB
authors: Kritchevsky
mesh_terms: 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*