title: Cognitive impairment after three decades of multiple sclerosis.
abstract: BACKGROUND
  Population-based studies of cognitive impairment in patients with multiple sclerosis (MS) with long disease duration are limited. The aim of this study was to evaluate long-term outcome and the predictors of cognitive impairment in a cohort of patients with MS.
  
  
  METHODS
  Patients living in Oslo, Norway, with definite MS and onset in 1940-1980 alive on 1 May 2006 were included. Disability was assessed by Expanded Disability Status Scale (EDSS). Cognitive functioning was assessed in terms of psychomotor speed, attention, learning/memory and executive functions.
  
  
  RESULTS
  A total of 123 patients was included. EDSS was < or =3.0 in 26% and > or =6.0 in 60% after mean disease duration of 34.5 years. Cognitive impairment was found in 48% of the patients eligible for neuropsychological evaluation (n = 84). Typical pattern was moderate impairment within areas of information processing, attention and memory. In the univariate analysis, younger onset age was significantly associated with cognitive impairment (P = 0.014). Younger onset age (P = 0.017) and disease course (secondary progressive vs. relapsing-remitting MS, P = 0.049) were significantly associated with cognitive impairment in the multivariate analysis.
  
  
  CONCLUSIONS
  After three decades of disease, half of the MS patients experienced reduced cognitive functioning; however, nearly one-third of the patients were only mildly disabled based on the EDSS. Younger onset age was associated with higher prevalence of cognitive impairment. A thorough evaluation of cognitive function in addition to EDSS is essential for evaluating long-term impairment in patients with MS.
authors.affiliation: Department of Neurology, Oslo University Hospital, Ullevål, Oslo, Norway. smec@uus.no
authors.forename: C
authors.initials: C
authors.lastname: Smestad
authors.forename: L
authors.initials: L
authors.lastname: Sandvik
authors.forename: N I
authors.initials: NI
authors.lastname: Landrø
authors.forename: E G
authors.initials: EG
authors.lastname: Celius
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D002648:Child; D003072:Cognition Disorders / Q000150:complications / Q000175:diagnosis*; D015331:Cohort Studies; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020528:Multiple Sclerosis, Chronic Progressive / Q000150:complications / Q000175:diagnosis*; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000150:complications / Q000175:diagnosis*; D009483:Neuropsychological Tests; D009664:Norway; D011379:Prognosis; D013997:Time Factors; D055815:Young Adult