title: Sun exposure and multiple sclerosis risk in Norway and Italy: The EnvIMS study.
abstract: The objective of this paper is to estimate the association between multiple sclerosis (MS) and measures of sun exposure in specific age periods in Norway and Italy.
  
  
  
  A total of 1660 MS patients and 3050 controls from Italy and Norway who participated in a multinational case-control study (EnvIMS) reported sun habits during childhood and adolescence.
  
  
  
  A significant association between infrequent summer outdoor activity and increased MS risk was found in Norway and in Italy. The association was strongest between the ages of 16 and 18 years in Norway (odds ratio (OR) 1.83, 95% confidence interval (CI) 1.30-2.59), and between birth and age 5 years in Italy (OR 1.56, 95% CI 1.16-2.10). In Italy a significant association was also found during winter (OR 1.42, 95% CI 1.03-1.97). Frequent sunscreen use between birth and the age of 6 years was associated with MS in Norway (OR 1.44, 95% CI 1.08-1.93) after adjusting for outdoor activity during the same period. Red hair (OR 1.67, 95% CI 1.06-2.63) and blonde hair (OR 1.36, 95% CI 1.09-1.70) were associated with MS after adjusting for outdoor activity and sunscreen use.
  
  
  
  Converging evidence from different measures underlines the beneficial effect of sun exposure on MS risk.
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Norway Department of Neurology, The Norwegian Multiple Sclerosis Competence Centre, Haukeland University Hospital, Norway kjetil.bjornevik@igs.uib.no.
authors.forename: Kjetil
authors.initials: K
authors.lastname: Bjørnevik
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Norway Department of Neurology, The Norwegian Multiple Sclerosis Competence Centre, Haukeland University Hospital, Norway.
authors.forename: Trond
authors.initials: T
authors.lastname: Riise
authors.affiliation: Department of Biomedical and Surgical Sciences, Section of Clinical Neurology, University of Ferrara, Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Casetta
authors.affiliation: Clinic of Neurology, Faculty of Medicine, University of Belgrade, Serbia.
authors.forename: Jelena
authors.initials: J
authors.lastname: Drulovic
authors.affiliation: Department of Biomedical and Surgical Sciences, Section of Clinical Neurology, University of Ferrara, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Granieri
authors.affiliation: Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Norway Department of Neurology, Akershus University Hospital, Norway.
authors.forename: Trygve
authors.initials: T
authors.lastname: Holmøy
authors.affiliation: Department of Clinical Neurology, University of Tromsø, Norway Department of Neurology, University Hospital of North Norway, Norway.
authors.forename: Margitta T
authors.initials: MT
authors.lastname: Kampman
authors.affiliation: Division of Neurology, Department of Clinical and Experimental Medicine, UHL, County Council, Linköping University, Sweden.
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Landtblom
authors.affiliation: Griesheim, Darmstadt, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Lauer
authors.affiliation: Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Norway Institute of Immunology, Oslo University Hospital Rikshospitalet, Norway.
authors.forename: Andreas
authors.initials: A
authors.lastname: Lossius
authors.affiliation: Department of Epidemiology and Biostatistics and Occupational Health, McGill University, Canada.
authors.forename: Sandra
authors.initials: S
authors.lastname: Magalhaes
authors.affiliation: Department of Neurology, The Norwegian Multiple Sclerosis Competence Centre, Haukeland University Hospital, Norway The KG Jebsen Centre for MS-Research, Department of Clinical Medicine, University of Bergen, Bergen, Norway.
authors.forename: Kjell-Morten
authors.initials: KM
authors.lastname: Myhr
authors.affiliation: Institute of Epidemiology, Faculty of Medicine, University of Belgrade, Serbia.
authors.forename: Tatjana
authors.initials: T
authors.lastname: Pekmezovic
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Norway Department of Neurology, The Norwegian Multiple Sclerosis Competence Centre, Haukeland University Hospital, Norway.
authors.forename: Kristin
authors.initials: K
authors.lastname: Wesnes
authors.affiliation: Research Institute of the McGill University Health Centre, Canada.
authors.forename: Christina
authors.initials: C
authors.lastname: Wolfson
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Norway Department of Clinical and Experimental Medicine, University of Sassari, Italy.
authors.forename: Maura
authors.initials: M
authors.lastname: Pugliatti
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D006200:Hair Color; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007558:Italy / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D009664:Norway / Q000453:epidemiology; D016017:Odds Ratio; D065840:Protective Factors; D018570:Risk Assessment; D012307:Risk Factors; D012621:Seasons; D013472:Sunlight; D013473:Sunscreening Agents / Q000008:administration & dosage; D013997:Time Factors; D055815:Young Adult
chemical_list: D013473:Sunscreening Agents
keywords: Multiple sclerosis; epidemiology; sun exposure; sunscreen; vitamin D