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Association Between Time Spent Outdoors and Risk of Multiple Sclerosis
Prince Sebastian1, Nicolas Cherbuin1, Lisa F Barcellos1
1From the Australian National University Medical School (P.S.), Centre for Research on Ageing, Health and Wellbeing (N.C.), and National Centre for Epidemiology and Population Health (R.L.), Australian National University, Canberra; Division of Epidemiology (L.F.B.), University of California Berkeley; Department of Pediatrics (S.R., C.C.), University of Utah School of Medicine, Salt Lake City; Pediatric Multiple Sclerosis Center (J.H.) and Department of Neurology (E.W.), University of California San Francisco; Pediatric Multiple Sclerosis Center (G.S.A.), Loma Linda University Children's Hospital, CA; MS Comprehensive Care Center (L.K.), New York University Langone, NY; Pediatric Multiple Sclerosis and Related Disorders Program (L.B., M. Gorman), Boston Children's Hospital, MA; Division of Pediatric Neurology (M.C.), University of Utah Primary Children's Hospital, Salt Lake City; Partners Pediatric Multiple Sclerosis Center (T.C.), Massachusetts General Hospital for Children, Boston; Department of Radiology (M. Goyal), Washington University St. Louis, MO; Department of Neurology (B.G.), University of Texas Southwestern, Dallas; Pediatric-Onset Demyelinating Diseases and Autoimmune Encephalitis Center (S.M.), St. Louis Children's Hospital, Washington University School of Medicine, MO; Mayo Clinic Pediatric Multiple Sclerosis Center (M.R.), Mayo Clinic, Rochester, MN; Department of Pediatric Neurology (J.R.), Northwestern Feinberg School of Medicine, Chicago, IL; Children's Hospital Colorado (T.S.), University of Colorado, Denver; Division of Neurology (A.W.), Children's Hospital of Philadelphia, PA; Pediatric Multiple Sclerosis Center (B.W.-G.), Jacobs Neurological Institute, State University of New York Buffalo; and Department of Neurosciences (J.G.), University of California San Diego.
Insights
Spending more time outdoors in the summer significantly reduces the risk of pediatric multiple sclerosis (MS). Higher ultraviolet radiation (UVR) exposure also appears protective, suggesting sun exposure is key for preventing childhood MS.
Area of Science:
- Environmental Health
- Pediatric Neurology
- Epidemiology
Background:
- Pediatric-onset multiple sclerosis (MS) is a debilitating neurological condition.
- The role of environmental factors, specifically sun exposure and ultraviolet radiation (UVR), in pediatric MS risk is not fully understood.
Purpose of the Study:
- To investigate the association between sun exposure, UVR dose, and the risk of developing pediatric-onset MS.
Main Methods:
- A case-control study involving 332 children with MS and 534 controls, matched for age and sex.
- Data collected on time spent outdoors, sun protection use, and ambient summer UVR dose.
- Multivariable conditional logistic regression was used for analysis, adjusting for numerous potential confounders.
Main Results:
- Increased time spent outdoors during summer was strongly associated with reduced odds of pediatric MS, showing a dose-response relationship.
- Higher ambient summer UVR dose was also found to be protective against MS.
- Spending 1-2 hours outdoors daily was associated with a significant reduction in MS risk (AOR 0.19).
Conclusions:
- Greater summer sun exposure may be a significant protective factor against the development of pediatric MS.
- Residing in areas with higher UVR may also reduce the risk of childhood MS.
- These findings suggest a potential causal link between sun exposure and reduced pediatric MS risk.
Background And Objectives:
This study aims to determine the contributions of sun exposure and ultraviolet radiation (UVR) exposure to risk of pediatric-onset multiple sclerosis (MS).
Methods:
Children with MS and controls recruited from multiple centers in the United States were matched on sex and age. Multivariable conditional logistic regression was used to investigate the association of time spent outdoors daily in summer, use of sun protection, and ambient summer UVR dose in the year before birth and the year before diagnosis with MS risk, with adjustment for sex, age, race, birth season, child's skin color, mother's education, tobacco smoke exposure, being overweight, and Epstein-Barr virus infection.
Results:
Three hundred thirty-two children with MS (median disease duration 7.3 months) and 534 controls were included after matching on sex and age. In a fully adjusted model, compared to spending <30 minutes outdoors daily during the most recent summer, greater time spent outdoors was associated with a marked reduction in the odds of developing MS, with evidence of dose-response (30 minutes-1 hour: adjusted odds ratio [AOR] 0.48, 95% confidence interval [CI] 0.23-0.99, p = 0.05; 1-2 hours: AOR 0.19, 95% CI 0.09-0.40, p < 0.001). Higher summer ambient UVR dose was also protective for MS (AOR 0.76 per 1 kJ/m2, 95% CI 0.62-0.94, p = 0.01).
Discussion:
If this is a causal association, spending more time in the sun during summer may be strongly protective against developing pediatric MS, as well as residing in a sunnier location.
