title: Detecting cognitive fatigue in multiple sclerosis: method matters.
abstract: BACKGROUND
  Fatigue is a frequently reported and debilitating symptom in multiple sclerosis (MS). Cognitive fatigue (CF) can be defined as decreased performance with sustained cognitive effort. The effectiveness of the Paced Auditory Serial Addition Task (PASAT) and the Computerized Test of Information Processing (CTIP) at detecting CF was examined, as was the impact of methodology. Subjective fatigue was measured using the Fatigue Impact Scale (FIS). The relationship between objective and subjective fatigue was examined.
  
  
  METHODS
  70 MS and 72 healthy controls (HC) completed the PASAT (3″ and 2″), CTIP, and FIS as part of a larger battery.
  
  
  RESULTS
  The MS and HCs performed worse on cognitively demanding tasks. Depending on methodology, PASAT performance varied between groups at the 3″ inter-stimulus interval (ISI) and the MS group showed greater susceptibility to CF as their ability to meet task demands declined as the task progressed. CTIP performance for both groups varied differently over time depending on task. The relationship between subjective and objective measures of fatigue varied depending on methodology, with PASAT generally correlating well with the Cognitive Dimension of the FIS.
  
  
  CONCLUSIONS
  The PASAT is a sensitive measure of CF in MS. Additional information is obtained with different scoring methods, with percent dyad scoring method being most sensitive to CF. The ability to detect a relationship between objective and subjective measures varied with methodology.
authors.affiliation: Neuropsychology Service, The Ottawa Hospital, Ottawa, Canada. lwalker@ottawahospital.on.ca
authors.forename: L A S
authors.initials: LA
authors.lastname: Walker
authors.forename: J A
authors.initials: JA
authors.lastname: Berard
authors.forename: L I
authors.initials: LI
authors.lastname: Berrigan
authors.forename: L M
authors.initials: LM
authors.lastname: Rees
authors.forename: M S
authors.initials: MS
authors.lastname: Freedman
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D003071:Cognition / Q000502:physiology; D003072:Cognition Disorders / Q000150:complications / Q000175:diagnosis* / Q000523:psychology; D005221:Fatigue / Q000150:complications / Q000175:diagnosis* / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000150:complications / Q000523:psychology*; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000502:physiology*