title: P300 amplitude and response speed relate to preserved cognitive function in relapsing-remitting multiple sclerosis.
abstract: OBJECTIVE
  To explore if cognitive impairment in relapsing-remitting multiple sclerosis (RRMS) is associated with abnormal neural function and if there is evidence of neural compensatory mechanisms.
  
  
  METHODS
  Seventy-two RRMS patients and 89 healthy control subjects were included in a cross-sectional study. Event-related brain potential (P300) and response time (RT) were recorded with visual and auditory choice reaction tasks. Cognitive function was evaluated with an 18 item test battery.
  
  
  RESULTS
  Patients had a decrease in cognitive function (p<0.001 for global score) and increased visual P300 amplitude frontally. P300 amplitude was normal in other brain areas and RT was normal. P300 latency was normal except for an increase in auditory latency occipitally. Cognitive performance correlated positively with parietal P300 amplitude in patients but not in controls. Cognition had stronger correlation (negative) with RT in patients than in controls.
  
  
  CONCLUSIONS
  Patients with low P300 amplitude and long RT were more often cognitively impaired. This indicates that general factors such as signal amplitude and speed are limiting for cognitive function in RRMS patients. The increase in frontal P300 amplitude may be a compensatory effect.
  
  
  CONCLUSIONS
  Our findings suggest that high amplitude and fast speed may be protective against cognitive impairment.
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Mathias
authors.initials: M
authors.lastname: Sundgren
authors.affiliation: Neurophysics Group, Department of Neurology, Campus Benjamin Franklin, Charité - University Medicine Berlin, Germany; Bernstein Center for Computational Neuroscience, Berlin, Germany.
authors.forename: Vadim V
authors.initials: VV
authors.lastname: Nikulin
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Liselotte
authors.initials: L
authors.lastname: Maurex
authors.affiliation: Institute of Gerontology, School of Health Sciences, Jönköping University, Jönköping, Sweden.
authors.forename: Åke
authors.initials: Å
authors.lastname: Wahlin
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Piehl
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden. Electronic address: tom.brismar@ki.se.
authors.forename: Tom
authors.initials: T
authors.lastname: Brismar
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D003071:Cognition / Q000502:physiology*; D003430:Cross-Sectional Studies; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000175:diagnosis* / Q000503:physiopathology; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000502:physiology*
keywords: Cognitive function; Event-related potential; Multiple sclerosis; P300; Response time