title: Disruption of sitting balance after stroke: influence of spoken output.
abstract: OBJECTIVE
  To identify the extent of dual task interference between cognitive and motor tasks, (cognitive motor interference (CMI)) in sitting balance during recovery from stroke; to compare CMI in sitting balance between stroke and non-stroke groups; and to record any changes to CMI during sitting that correlate with functional recovery.
  
  
  METHODS
  36 patients from stroke rehabilitation settings in three NHS trusts. Healthy control group: 21 older volunteers. Measures of seated postural sway were taken in unsupported sitting positions, alone, or concurrently with either a repetitive utterance task or an oral word category generation task. Outcome measures were variability of sway area, path length of sway, and the number of valid words generated.
  
  
  RESULTS
  Stroke patients were generally less stable than controls during unsupported sitting tasks. They showed greater sway during repetitive speech compared with quiet sitting, but did not show increased instability to posture between repetitive speech and word category generation. When compared with controls, stroke patients experienced greater dual task interferences during repetitive utterance but not during word generation. Sway during repetitive speech was negatively correlated with concurrent function on the Barthel ADL index.
  
  
  CONCLUSIONS
  The stroke patients showed postural instability and poor word generation skills. The results of this study show that the effort of verbal utterances alone was sufficient to disturb postural control early after stroke, and the extent of this instability correlated with concomitant Barthel ADL function.
authors.affiliation: Institute of Psychological Sciences, University of Leeds, Leeds LS2 9JT, UK. c.harley@leeds.ac.uk
authors.forename: C
authors.initials: C
authors.lastname: Harley
authors.forename: J E
authors.initials: JE
authors.lastname: Boyd
authors.forename: J
authors.initials: J
authors.lastname: Cockburn
authors.forename: C
authors.initials: C
authors.lastname: Collin
authors.forename: P
authors.initials: P
authors.lastname: Haggard
authors.forename: J P
authors.initials: JP
authors.lastname: Wann
authors.forename: D T
authors.initials: DT
authors.lastname: Wade
mesh_terms: D000203:Activities of Daily Living / Q000145:classification; D000368:Aged; D001288:Attention / Q000502:physiology; D002544:Cerebral Infarction / Q000175:diagnosis / Q000503:physiopathology* / Q000534:rehabilitation; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D008609:Mental Status Schedule / Q000706:statistics & numerical data; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D010700:Phonetics; D004856:Postural Balance / Q000502:physiology*; D011594:Psychometrics / Q000706:statistics & numerical data; D012660:Semantics; D013068:Speech Production Measurement; D013223:Statistics as Topic; D014705:Verbal Behavior / Q000502:physiology*; D014706:Verbal Learning / Q000502:physiology; D014825:Vocabulary