Kids who get more sunlight may have lower risk for MS

Increased sunlight exposure may offer significant protection against development of pediatric MS, according to study results published in Neurology.

“MS etiology is understood to be a combination of genetic predisposition, infectious exposures and other environmental and behavioral risk factors,” Prince Sebastian, PhB, of the Australian National University Medical School, and colleagues wrote. “In particular, low sun exposure, low ultraviolet radiation (UVR) exposure and low vitamin D status have been well-characterized as environmental risk factors for adult-onset MS, with a particular increase in risk associated with insufficient sun exposure in childhood. However, to date, research on sun/UVR exposure in MS has mostly been limited to adult populations.”

Researchers analyzed data from a multicenter case-control study that examined environmental risk factors for pediatric MS to determine whether sun exposure, measured as time spent outdoors, and UVR exposure, measured as ambient UVR dose, correlated with risk for pediatric MS. Following recruitment from multiple U.S. centers, 332 children with MS (median disease duration, 7.3 months) were matched with 534 controls based on sex and age. Via multivariable conditional logistic regression, researchers examined whether time spent outdoors each day in the summer, use of sun protection and ambient summer UVR dose in the year before birth and the year before diagnosis affected MS risk. They adjusted for sex, age, race, birth season, child’s skin color, mother’s education, tobacco smoke exposure, being overweight and Epstein-Barr virus infection.

A fully adjusted model revealed more time spent outdoors correlated with a significant reduction in the risk for MS development compared with spending less than 30 minutes outdoors each day during the most recent summer. Sebastian and colleagues reported evidence of dose-response ([30 minutes to 1 hour: adjusted OR = 0.48; 95% CI, 0.23-0.99]; [1hour to 2 hours: adjusted OR = 0.19; 95% CI, 0.09-0.4]). Higher summer ambient UVR dose also protected against MS.

“Clarifying the causal effect of modifiable risk factors, such as sun exposure and vitamin D status, could reduce the disease burden associated with MS,” Sebastian and colleagues wrote. “Our findings suggest that advising regular time in the sun of at least 30 minutes daily during summer [and] using sun protection as needed, especially for first-degree relatives of MS patients, may be a worthwhile intervention to reduce the incidence of pediatric MS.”