title: The Role of Environment and Lifestyle in Determining the Risk of Multiple Sclerosis.
abstract: MS is a complex disease where both genetic and environmental factors contribute to disease susceptibility. The substantially increased risk of developing MS in relatives of affected individuals gives solid evidence for a genetic base for susceptibility, whereas the modest familial risk, most strikingly demonstrated in the twin studies, is a very strong argument for an important role of lifestyle/environmental factors in determining the risk of MS, sometimes interacting with MS risk genes. Lifestyle factors and environmental exposures are harder to accurately study and quantify than genetic factors. However, it is important to identify these factors since they, as opposed to risk genes, are potentially preventable. We have reviewed the evidence for environmental factors that have been repeatedly shown to influence the risk of MS: Epstein-Barr virus (EBV) infection, ultraviolet radiation (UVR) exposure habits /vitamin D status, and smoking. We have also reviewed a number of additional environmental factors, published in the past 5 years, that have been described to influence MS risk. Independent replication, preferably by a variety of methods, may give still more firm evidence for their involvement.
authors.affiliation: Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden. anna.hedstrom@ki.se.
authors.forename: Anna Karin
authors.initials: AK
authors.lastname: Hedström
authors.affiliation: Department of Clinical Neurosciences, Neuroimmunology Unit, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Tomas
authors.initials: T
authors.lastname: Olsson
authors.affiliation: Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Alfredsson
mesh_terms: D004777:Environment; D020031:Epstein-Barr Virus Infections; D059647:Gene-Environment Interaction; D004854:Herpesvirus 4, Human; D006801:Humans; D008019:Life Style; D009103:Multiple Sclerosis / Q000453:epidemiology* / Q000235:genetics; D012306:Risk; D012907:Smoking / Q000009:adverse effects; D014466:Ultraviolet Rays
keywords: Epstein–Barr virus; Gene–environment interactions; Multiple sclerosis; Obesity; Smoking; Vitamin D