title: [Smoking and multiple sclerosis].
abstract: BACKGROUND
  Multiple sclerosis (MS) is a complex autoimmune disease of unknown etiology, in which genetic and environmental factors interact and determine the disease susceptibility. In recent years, smoking effect has been one of the emerging environmental factors in the study of MS and has been associated with an increased susceptibility and an increase in disease progression.
  
  
  OBJECTIVE
  To review the current evidence on the role of smoking in MS.
  
  
  METHODS
  The review includes an update of studies that have analyzed different aspects of tobacco in MS, including the potential pathogenic pathways involved, association of smoking and risk of MS, interactions with other risk factors and the effect of smoking in the disease course.
  
  
  CONCLUSIONS
  Observational studies show that smoking significantly increases the risk of MS (odds ratio~1.5) and is an independent risk factor. However, MS is a complex disease and this risk may be modified depending on the interaction with other genetic and environmental factors. The role of smoking as a progression factor is more controversial, with confronted results and highly variable studies, making it difficult to draw any conclusion. The mechanisms by which smoking may modify the risk and progression of the disease have to be further investigated.
authors: Hospital Universitario Donostia, San Sebastian, Espana.
authors: Maialen
authors: M
authors: Arruti
authors: Tamara
authors: T
authors: Castillo-Triviño
authors: Nerea
authors: N
authors: Egüés
authors: Javier
authors: J
authors: Olascoaga
mesh_terms: D018450:Disease Progression; D004198:Disease Susceptibility; D006801:Humans; D009103:Multiple Sclerosis / Q000209:etiology*; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*