title: Influence of executive function on locomotor function: divided attention increases gait variability in Alzheimer's disease.
abstract: OBJECTIVE
  To evaluate how cognitive function and divided attention affect gait in Alzheimer's disease (AD).
  
  
  METHODS
  Cross-sectional intervention study with subjects serving as their own controls.
  
  
  METHODS
  Inpatient unit and outpatient clinic for patients with dementia located at a Veterans Affairs Medical Center.
  
  
  METHODS
  Twenty-eight patients diagnosed with probable AD.
  
  
  METHODS
  Performance of a cognitive task (repeating random digits) while walking.
  
  
  METHODS
  Neuropsychological measures including clock drawing, verbal fluency, and digit span were obtained along with the Clinical Dementia Rating and Mini-Mental State Examination, the measures of dementia severity. Gait speed and stride-to-stride variability of gait rhythm were measured, once during normal walking and once during dual-task walking.
  
  
  RESULTS
  During usual walking, subjects walked slowly and with greater gait variability than older adults without AD. Gait speed was significantly reduced (P<.012) and gait variability increased with dual-task walking (P<.007). The effect on gait variability was larger than the effect on gait speed (P<.015). Executive and neuropsychological function were significantly (P<.02) associated with the increased gait variability that occurred when walking with divided attention but not with gait speed or usual, single-task walking measures of gait.
  
  
  CONCLUSIONS
  Divided attention markedly impairs the ability of patients with AD to regulate the stride-to-stride variations in gait timing. This susceptibility to distraction and its effect on stride time variability, a measure of gait unsteadiness, could partially explain the predilection to falling observed in patients with dementia. The results also support the concept that persons with AD have significant impairments in the cognitive domain of attention and that locomotor function relies upon cognitive, especially executive, function.
authors.affiliation: Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA. psherida@caregroup.harvard.edu
authors.forename: Pamela L
authors.initials: PL
authors.lastname: Sheridan
authors.forename: Judi
authors.initials: J
authors.lastname: Solomont
authors.forename: Neil
authors.initials: N
authors.lastname: Kowall
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Hausdorff
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000544:Alzheimer Disease / Q000503:physiopathology*; D003196:Computer Graphics; D003430:Cross-Sectional Studies; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D010865:Pilot Projects; D011597:Psychomotor Performance; D018709:Statistics, Nonparametric; D014481:United States; D016138:Walking / Q000502:physiology