title: Physical activity is associated with a decreased multiple sclerosis risk: The EnvIMS study.
abstract: The lifestyle factors smoking and obesity have been associated with the risk of multiple sclerosis (MS). Physical activity (PA) may also be of importance.
  
  
  
  To examine the association between PA and MS risk in Italy, Norway, and Sweden and to evaluate the possible influence by established risk factors.
  
  
  
  In this case-control study, 1904 cases and 3694 controls were asked to report their average weekly amounts of light and vigorous PA during adolescence on a scale ranging from none to more than 3 hours activity. We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) and adjusted for potential confounders.
  
  
  
  Vigorous PA was inversely associated with MS risk in the pooled analysis ( p-trend < 0.001) with an age- and sex-adjusted OR of 0.74 (95% CI: 0.63-0.87) when comparing the highest and lowest levels. Adjusting for outdoor activity, infectious mononucleosis, body size, and smoking yielded similar results. The association was present in all countries and was not affected by exclusion of patients with early disease onset. Light PA was not associated with the risk of MS.
  
  
  
  Our findings suggest that vigorous PA can modify the risk of developing MS independent of established risk factors.
authors.affiliation: Department of Clinical Medicine, University of Bergen, Bergen, Norway/The Norwegian Multiple Sclerosis Competence Centre, Department of Neurology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Kristin
authors.initials: K
authors.lastname: Wesnes
authors.affiliation: Department of Clinical Medicine, University of Bergen, Bergen, Norway/The Norwegian Multiple Sclerosis Registry and Biobank, Department of Neurology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Kjell-Morten
authors.initials: KM
authors.lastname: Myhr
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway/The Norwegian Multiple Sclerosis Competence Centre, Department of Neurology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Trond
authors.initials: T
authors.lastname: Riise
authors.affiliation: Department of Clinical Medicine, University of Bergen, Bergen, Norway/The Norwegian Multiple Sclerosis Competence Centre, Department of Neurology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Marianna
authors.initials: M
authors.lastname: Cortese
authors.affiliation: Department of Biomedical and Specialty Surgical Sciences, Section of Clinical Neurology, University of Ferrara, Ferrara, Italy/Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.
authors.forename: Maura
authors.initials: M
authors.lastname: Pugliatti
authors.affiliation: Division of Neurology, Department of Clinical and Experimental Medicine, University of Linköping, Linköping, Sweden.
authors.forename: Inger
authors.initials: I
authors.lastname: Boström
authors.affiliation: Division of Neurology, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden/Department of Neuroscience/Neurology, Uppsala University, Uppsala, Sweden.
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Landtblom
authors.affiliation: Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, QC, Canada/The Research Institute of the McGill University Health Centre, Montreal, QC, Canada.
authors.forename: Christina
authors.initials: C
authors.lastname: Wolfson
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway/The Norwegian Multiple Sclerosis Competence Centre, Department of Neurology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Kjetil
authors.initials: K
authors.lastname: Bjørnevik
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D015444:Exercise; D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000453:epidemiology*; D009664:Norway / Q000453:epidemiology; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult
keywords: Multiple sclerosis; case–control study; epidemiology; exercise; physical activity; risk factors