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Environmental factors in early childhood are associated with multiple sclerosis: a case-control study

Silja Conradi12, Uwe Malzahn3, Franziska Schröter1, Friedemann Paul4, Sabine Quill1, Eike Spruth5, Lutz Harms1, Florian Then Bergh2, Anna Ditzenbach6, Thomas Georgi7, Peter Heuschmann3 and Berit Rosche1*

Author Affiliations

1 Department of Neurology & Experimental Neurology, Charité - Universitätsmedizin Berlin, Charitéplatz 1, Berlin, 10117, Germany

2 Department of Neurology, University Hospital Leipzig, Liebigstraße 20, Leipzig, 04103, Germany

3 Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Charitéplatz 1, Berlin, 10117, Germany

4 NeuroCure Clinical Research Center (NCRC), Charité - Universitätsmedizin Berlin, Charitéplatz 1, Berlin, 10117, Germany

5 Department of Neuropsychiatry and Laboratory of Molecular Psychiatry, Charité -Universitätsmedizin Berlin, Charitéplatz 1, Berlin, 10117, Germany

6 General Practitioner, Berliner Straße 14b, Berlin, 14169, Germany

7 General Practitioner, Prenzlauer Allee 90, Berlin, 10409, Germany

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BMC Neurology 2011, 11:123  doi:10.1186/1471-2377-11-123

Published: 6 October 2011



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.


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.


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.


The hygiene hypothesis may play a role in the occurrence of MS and could explain disease distribution and increasing incidence.