Children and adults who spend more time outside are less likely to develop multiple sclerosis (MS) in later life, a US study has suggested.
Although previous studies have highlighted how UV-B rays from sunlight can be protective during childhood years, University of British Columbia neurology Professor Helen Tremlett and her team decided to extend the association into adulthood.
In the online issue of the journal Neurology, Tremlett looked at 151 cases with MS and 235 age-matched controls from the Nurses’ Health Study. Cohorts completed summer, winter and lifetime sun exposure history questionnaires.
Most of the participants were white (98%) and the mean age at MS onset was 39.5 years. The results showed that living in high UV-B areas before MS onset was associated with a 45% lower MS risk.
Similar reduced risks (51%–52%) for medium or high exposure were observed at ages 5 to 15 years and at 5 to 15 years before MS onset.
At age 5 to 15 years, living in a high UV-B area and having high summer sun exposure were associated with a lower MS risk.
Tremlett and her team concluded that living in high ambient UV-B areas during childhood and the years leading up to MS onset was associated with a lower MS risk. High summer sun exposure in high ambient UV-B areas was also associated with a reduced risk.