title: Reduced Dual-Task Performance in MS Patients Is Further Decreased by Muscle Fatigue.
abstract: BACKGROUND
  Multiple sclerosis (MS) can be accompanied by motor, cognitive, and sensory impairments. Additionally, MS patients often report fatigue as one of their most debilitating symptoms. It is, therefore, expected that MS patients will have difficulties in performing cognitive-motor dual tasks (DTs), especially in a fatiguing condition.
  
  
  OBJECTIVE
  To determine whether MS patients are more challenged by a DT than controls in a fatiguing and less-fatiguing condition and whether DT performance is associated with perceived fatigue.
  
  
  METHODS
  A group of 19 MS patients and 19 age-, sex-, and education-matched controls performed a cognitive task (2-choice reaction time task) separately or concurrent with a low-force or a high-force motor task (index finger abduction at 10% or 30% maximal voluntary contraction).
  
  
  RESULTS
  MS patients performed less well on a cognitive task than controls. Cognitive task performance under DT conditions decreased more for MS patients. Moreover, under high-force DT conditions, cognitive performance declined in both groups but to a larger degree for MS patients. Besides a decline in cognitive task performance, MS patients also showed a stronger decrease in motor performance under high-force DT conditions. DT costs were positively related to perceived fatigue as measured by questionnaires.
  
  
  CONCLUSIONS
  Compared with controls, MS patients performed less well on DTs as demonstrated by a reduction in both cognitive and motor performances. This performance decrease was stronger under fatiguing conditions and was related to the sense of fatigue of MS patients. These data illustrate problems that MS patients may encounter in daily life because of their fatigue.
authors.affiliation: Department of Neuroscience, University Medical Center Groningen, University of Groningen, The Netherlands.
authors.forename: Ria
authors.initials: R
authors.lastname: Wolkorte
authors.affiliation: Department of Neurology, University Medical Center Groningen, The Netherlands.
authors.forename: Dorothea J
authors.initials: DJ
authors.lastname: Heersema
authors.affiliation: Department of Neuroscience, University Medical Center Groningen, University of Groningen, The Netherlands.
authors.forename: Inge
authors.initials: I
authors.lastname: Zijdewind
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000209:etiology*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D005385:Fingers / Q000294:innervation; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009103:Multiple Sclerosis / Q000150:complications*; D009119:Muscle Contraction / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology*; D009483:Neuropsychological Tests; D017063:Outcome Assessment, Health Care; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time; D013997:Time Factors; D055815:Young Adult
keywords: cognitive performance; cognitive-motor task; dual-task costs; fatigability; force; reaction times