title: Task-dependent deterioration of balance underpinning cognitive-postural interference in MS.
abstract: OBJECTIVE
  To investigate which concurrent cognitive task (if any) had the most detrimental effect on balance control of patients with multiple sclerosis (MS).
  
  
  METHODS
  In a dual-task experiment, we evaluated the reciprocal effect of simultaneously performing a postural and a cognitive task on balance and cognition in 52 patients and 26 sex- and age-matched controls. Balance was assessed by static posturography, while cognition was scored as number of correct items at 3 different neuropsychological tests, i.e., the Symbol Digit Modalities Test (SDMT), word list generation (WLG), and Stroop Color-Word Test (SCWT).
  
  
  RESULTS
  In both single and dual-task conditions, the patients had larger postural sway and worse scores at SDMT, WLG, and SCWT than the controls (p < 0.05). Test-retest reliability was excellent for all dual-task metrics (85%-94%). By means of 2-way analyses of the variance, we found significant main effects of dual task on balance, regardless of the concurrent cognitive task (p < 0.001). There was no main effect of dual task on cognitive performance across all the 3 task conditions (p ≥ 0.1). We observed a significant condition-by-group interaction effect on balance only when the SCWT was administered as concurrent task (p = 0.01), indicating a greater dual-task cost of balance for the patients than controls (53% vs 28%, p = 0.04).
  
  
  CONCLUSIONS
  We suggest that tasks exploring executive functions involved in discriminating conflicting stimuli may be the most suitable to unmask the cognitive-postural interference phenomenon in patients with MS. This may support the hypothesis that MS-related damage constrains brain networks to subserve both postural control and executive functions.
authors: From the Department of Neurology and Psychiatry, Sapienza University, Rome, Italy. luca.prosperini@uniroma1.it.
authors: Luca
authors: L
authors: Prosperini
authors: From the Department of Neurology and Psychiatry, Sapienza University, Rome, Italy.
authors: Letizia
authors: L
authors: Castelli
authors: From the Department of Neurology and Psychiatry, Sapienza University, Rome, Italy.
authors: Francesca
authors: F
authors: De Luca
authors: From the Department of Neurology and Psychiatry, Sapienza University, Rome, Italy.
authors: Francesca
authors: F
authors: Fabiano
authors: From the Department of Neurology and Psychiatry, Sapienza University, Rome, Italy.
authors: Ilaria
authors: I
authors: Ferrante
authors: From the Department of Neurology and Psychiatry, Sapienza University, Rome, Italy.
authors: Laura
authors: L
authors: De Giglio
mesh_terms: D001288:Attention; D003071:Cognition; D003430:Cross-Sectional Studies; D056344:Executive Function; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009103:Multiple Sclerosis / Q000503:physiopathology* / Q000523:psychology*; D009483:Neuropsychological Tests; D004856:Postural Balance; D015203:Reproducibility of Results