Related Experiment Videos
Past exposure to sun, skin phenotype, and risk of multiple sclerosis: case-control study
I A F van der Mei1, A-L Ponsonby, T Dwyer
1Menzies Centre for Population Health Research, University of Tasmania, Hobart, TAS 7000, Australia. Ingrid.vanderMei@utas.edu.au
Objective:
To examine whether past high sun exposure is associated with a reduced risk of multiple sclerosis.
Design:
Population based case-control study.
Setting:
Tasmania, latitudes 41-3 degrees S.
Participants:
136 cases with multiple sclerosis and 272 controls randomly drawn from the community and matched on sex and year of birth.
Main Outcome Measure:
Multiple sclerosis defined by both clinical and magnetic resonance imaging criteria.
Results:
Higher sun exposure when aged 6-15 years (average 2-3 hours or more a day in summer during weekends and holidays) was associated with a decreased risk of multiple sclerosis (adjusted odds ratio 0.31, 95% confidence interval 0.16 to 0.59). Higher exposure in winter seemed more important than higher exposure in summer. Greater actinic damage was also independently associated with a decreased risk of multiple sclerosis (0.32, 0.11 to 0.88 for grades 4-6 disease). A dose-response relation was observed between multiple sclerosis and decreasing sun exposure when aged 6-15 years and with actinic damage.
Conclusion:
Higher sun exposure during childhood and early adolescence is associated with a reduced risk of multiple sclerosis. Insufficient ultraviolet radiation may therefore influence the development of multiple sclerosis.