The contribution of secondhand tobacco smoke exposure to pediatric multiple sclerosis risk

Mult Scler. 2019 Apr;25(4):515-522. doi: 10.1177/1352458518757089. Epub 2018 Feb 2.


Background: Pediatric acquired demyelinating syndromes (ADSs) are monophasic (mono-ADS) in 70% of cases and represent the first attack of multiple sclerosis (MS) in 30%. Secondhand tobacco smoke (SHS) exposure has been implicated as a risk factor for adult-onset MS. Little is known about whether SHS presents an additive risk beyond genetic factors and other environmental exposures associated with pediatric MS.

Methods: This study examined SHS exposure in 216 children with mono-ADS and 81 children with MS. Interactions between SHS, HLA-DRB1*15 alleles, serum 25-hydroxyvitamin D concentrations, and serological evidence of remote Epstein-Barr virus (EBV) exposure were evaluated.

Results: SHS exposure was more common in children with MS (37% exposed) compared to mono-ADS (29.5% exposed). Compared to mono-ADS, SHS exposure was not an independent risk factor for MS. When both SHS exposure and HLA-DRB1*15 were present, the odds for MS increased (odds ratio (OR) = 3.7; 95% confidence interval (CI): 1.17-11.9) compared to mono-ADS. Interactions between SHS and vitamin D or EBV did not associate with MS.

Conclusion: Exposure to SHS is a risk factor for central nervous system (CNS) demyelination. Results suggest that SHS exposure and HLA-DRB1*15 interact to increase risk for MS in children diagnosed with mono-ADS.

Keywords: Multiple sclerosis; epidemiology.

MeSH terms

  • Adolescent
  • Canada / epidemiology
  • Child
  • Demyelinating Diseases / chemically induced*
  • Demyelinating Diseases / epidemiology
  • Female
  • Gene-Environment Interaction*
  • HLA-DRB1 Chains / genetics*
  • Humans
  • Male
  • Multiple Sclerosis / chemically induced*
  • Multiple Sclerosis / epidemiology
  • Risk Factors
  • Tobacco Smoke Pollution / adverse effects*
  • Tobacco Smoke Pollution / statistics & numerical data


  • HLA-DRB1 Chains
  • HLA-DRB1*15 antigen
  • Tobacco Smoke Pollution