title: Investigating the phenomenon of "cognitive-motor interference" in multiple sclerosis by means of dual-task posturography.
abstract: BACKGROUND
  Two simultaneously performed tasks may compete for common brain network resources in patients with multiple sclerosis (MS), suggesting the occurrence of a cognitive-motor interference. While this phenomenon has been well described for walking and gait, data on static balance are scarce.
  
  
  METHODS
  In this cross-sectional study, 92 patients and 46 sex/age-matched healthy controls (HCs) were tested by means of static posturography under eyes opened (single-task condition) and while performing the Stroop word-colour task (dual-task condition), to estimate the dual-task cost (DTC) of standing balance. The patient group also underwent the Expanded Disability Status Scale, 25-foot walking test, 12-item MS walking scale, Modified Fatigue Impact Scale, and Symbol Digit Modalities Test.
  
  
  RESULTS
  Patients had larger postural sway under both single-task and dual-task conditions (p<0.001), as well as greater DTC of standing balance (p=0.021) than HCs. Although secondary progressive (SP) patients had larger sway in both conditions than relapsing-remitting (RR) patients (p<0.05), these latter ones exhibited a greater DTC of postural balance (p=0.045). Deficits in sustained attention and information processing speed, as assessed by the SDMT, were also independently associated with the magnitude of DTC of standing balance (p=0.005).
  
  
  CONCLUSIONS
  The phenomenon of cognitive-motor interference might be unmasked by a dual-task posturography and was associated with impaired sustained attention and information processing speed, especially in RR patients. The smaller DTC of standing balance observed in SP patients may be due to the ceiling effect of postural sway, or alternatively to the lack of postural reserve which constrained the more disabled patients to prioritize the balance over the cognitive task.
authors.affiliation: Dept of Neurology and Psychiatry, Sapienza University, Rome. Electronic address: luca.prosperini@uniroma1.it.
authors.forename: Luca
authors.initials: L
authors.lastname: Prosperini
authors.affiliation: Physical Therapy Unit, S. Andrea Hospital, Rome.
authors.forename: Letizia
authors.initials: L
authors.lastname: Castelli
authors.affiliation: Physical Therapy Unit, S. Andrea Hospital, Rome.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Sellitto
authors.affiliation: Dept of Neurology and Psychiatry, Sapienza University, Rome.
authors.forename: Francesca
authors.initials: F
authors.lastname: De Luca
authors.affiliation: Dept of Neurology and Psychiatry, Sapienza University, Rome.
authors.forename: Laura
authors.initials: L
authors.lastname: De Giglio
authors.affiliation: Neurological Center of Latium, Rome.
authors.forename: Flavia
authors.initials: F
authors.lastname: Gurreri
authors.affiliation: Dept of Neurology and Psychiatry, Sapienza University, Rome.
authors.forename: Carlo
authors.initials: C
authors.lastname: Pozzilli
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D016022:Case-Control Studies; D003071:Cognition / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D005684:Gait / Q000502:physiology; D006801:Humans; D008297:Male; D009103:Multiple Sclerosis / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D016138:Walking / Q000502:physiology
keywords: Attention; Balance; Cognition; Dual-task cost; Multiple sclerosis; Posturography