title: The effects of a short-term memory task on postural control of stroke patients.
abstract: BACKGROUND
  Many studies have been conducted on the changes in the balance capabilities of stroke patients. However, results regarding the effects of dual-task activities on postural control in these patients have been variable.
  
  
  OBJECTIVE
  To evaluate the effects of a short-term memory task on the sway characteristics of stroke patients.
  
  
  METHODS
  Center of pressure (COP) fluctuations were measured in three levels of postural difficulty (rigid surface with closed and open eyes and foam surface with closed eyes), as well as two levels of cognitive difficulty (easy and difficult). COP parameters included mean velocity, standard deviation of velocity in both medial-lateral (M.L) and anterior-posterior (A.P) directions, total phase plane portrait, area. Nineteen stroke patients and 19 gender, age, height, and weight matching healthy volunteers participated in this study.
  
  
  RESULTS
  Our findings indicate that mean velocity (F = 14.21, P = 0.001), standard deviation of velocity in both M.L (F = 17.50, P = 0.000) and A.P (F = 11.03, P = 0.002) directions, total phase plane portrait (F = 44.12, P = 0.001), and area (F = 13.95, P = 0.01) of center of pressure of patients were statistically greater than normal subjects, while significant interaction of group × postural difficulty and postural × cognitive difficulty were observed for all parameters of postural sway.
  
  
  CONCLUSIONS
  Different measures of postural sway showed complex response to postural and cognitive difficulties between stroke patients and normals. Cognitive error was not affected by the main effects of group and postural difficulty, while greatly increased at more difficult cognitive task (F = 75.73, P = 0.000).
authors.forename: Hajar
authors.initials: H
authors.lastname: Mehdizadeh
authors.forename: Ghorban
authors.initials: G
authors.lastname: Taghizadeh
authors.forename: Hamed
authors.initials: H
authors.lastname: Ghomashchi
authors.forename: Mohammad
authors.initials: M
authors.lastname: Parnianpour
authors.forename: Kinda
authors.initials: K
authors.lastname: Khalaf
authors.forename: Reza
authors.initials: R
authors.lastname: Salehi
authors.forename: Ali
authors.initials: A
authors.lastname: Esteki
authors.forename: Ismaeil
authors.initials: I
authors.lastname: Ebrahimi
authors.forename: Bahram
authors.initials: B
authors.lastname: Sangelaji
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term; D008875:Middle Aged; D004856:Postural Balance; D011187:Posture; D011597:Psychomotor Performance; D020521:Stroke / Q000523:psychology*
keywords: Dual-task,; Postural control,; Stroke