title: Event related potential and response time give evidence for a physiological reserve in cognitive functioning in relapsing-remitting multiple sclerosis.
abstract: Cognitive dysfunction is common in multiple sclerosis (MS). Different factors may moderate the degree of cognitive deficit. The aim of the present study was to distinguish different mechanisms for cognitive reserve in relapsing-remitting MS (RRMS). The effects of clinical variables (physical disability, depression), premorbid intelligence (years of education, vocabulary knowledge), visual event-related potential measures (P300) and response time (RT) were studied in RRMS patients (n=71) and healthy subjects (n=89). Patients with high P300 amplitude and short RT had better cognitive performance. This effect was significantly weaker in controls. High P300 and short RT may be physiological markers of a cognitive reserve in RRMS. In contrast, the association between cognitive scores and premorbid intelligence was similar in patients and in control subjects. The effects of physiological reserve and clinical variables were studied in a hierarchical linear regression model of cognitive performance in RRMS. P300 amplitude and RT explained a considerable amount of variance in global cognitive performance (34%, p<0.001). The effects of P300 and RT were not moderated by premorbid intelligence. Physical disability and depression added significantly to explained variance, and the final model accounted for 44% (p<0.001) of the variation. We conclude that physiological reserve is the strongest moderator of cognitive impairment in RRMS.
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden. Electronic address: mathias.sundgren@ki.se.
authors.forename: Mathias
authors.initials: M
authors.lastname: Sundgren
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: Liselotte
authors.initials: L
authors.lastname: Maurex
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Tom
authors.initials: T
authors.lastname: Brismar
mesh_terms: D000328:Adult; D003072:Cognition Disorders / Q000175:diagnosis* / Q000209:etiology*; D003863:Depression / Q000209:etiology; D004185:Disability Evaluation; D004569:Electroencephalography; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005221:Fatigue / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000150:complications*; D009483:Neuropsychological Tests; D011930:Reaction Time / Q000502:physiology*; D012044:Regression Analysis; D055815:Young Adult
keywords: Cognitive impairment; Cognitive reserve; Multiple sclerosis; P300; Response time