title: Environmental factors in early childhood are associated with multiple sclerosis: a case-control study.
abstract: BACKGROUND
  Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS) with increasing incidence mainly in high-income countries. One explanation of this phenomenon may be a higher prevalence of allergic and autoimmune diseases in industrialized countries as a consequence of otherwise beneficial advances in sanitation (hygiene hypothesis). We investigated environmental factors in early childhood associated with MS.
  
  
  METHODS
  A case-control study was performed of 245 MS patients and 296 population-based controls in Berlin. The study participants completed a standardized questionnaire on environmental factors in childhood and youth, including aspects of personal and community hygiene. Multivariable logistic regression analysis was performed to investigate factors in childhood and youth associated with the occurrence of MS.
  
  
  RESULTS
  Mean age was 46 years (range, 20-80) in the MS group and 42 years (range 18-80) in the control group, of which 73.9% in the MS and 61.5% in the control group were female. The multivariable analysis showed that having at least two older siblings (OR 0.54; p = 0.05, for individuals with two older siblings compared to individuals without older siblings), attending a day-care center (OR 0.5; p = 0.004) and growing up in an urban center with more than 100, 000 inhabitants (OR 0.43; p = 0.009) were factors independently associated with a lower chance for MS.
  
  
  CONCLUSIONS
  The hygiene hypothesis may play a role in the occurrence of MS and could explain disease distribution and increasing incidence.
authors: Department of Neurology & Experimental Neurology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, Berlin, 10117, Germany.
authors: Silja
authors: S
authors: Conradi
authors: Uwe
authors: U
authors: Malzahn
authors: Franziska
authors: F
authors: Schröter
authors: Friedemann
authors: F
authors: Paul
authors: Sabine
authors: S
authors: Quill
authors: Eike
authors: E
authors: Spruth
authors: Lutz
authors: L
authors: Harms
authors: Florian
authors: F
authors: Then Bergh
authors: Anna
authors: A
authors: Ditzenbach
authors: Thomas
authors: T
authors: Georgi
authors: Peter
authors: P
authors: Heuschmann
authors: Berit
authors: B
authors: Rosche
mesh_terms: D000328:Adult; D000368:Aged; D001604:Berlin; D016022:Case-Control Studies; D019049:Developed Countries; D004777:Environment; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D061148:Hygiene Hypothesis; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000453:epidemiology*; D012307:Risk Factors