MINNEAPOLIS – A new study suggests that children, teens and young adults who spend more time outdoors during the summer months and live in areas of the country that expose them to greater amounts of ultraviolet light have a lower risk of developing multiple sclerosis (MS) in childhood. Although rare, MS can develop in children, although most people start showing symptoms of the disease between the ages of 20 and 50. The research is published in the December 8, 2021 online issue of NeurologyÂ®, the medical journal of the American Academy of Neurology. The study also found that those who had been more exposed to the sun in their first year of life also had a lower risk of MS.
“It is difficult to provide advice on the best amounts of sun exposure to get while weighing the benefits against the risks,” said study author Emmanuelle Waubant, MD, PhD, of the University. from California to San Francisco and fellow of the American Academy of Neurology. âWe have found that spending between one and two hours outdoors per day has the most benefits, but spending as little as 30 minutes outdoors per day can reduce the risk of MS by about half. “
The study involved 332 people with MS who had the disease for an average of seven months. They were matched with 534 people of the same age and sex who did not have MS. The participants ranged from three to 22 years old.
Sun exposure was measured as time spent outdoors, use of sun protection such as a hat, clothing, and sunscreen, plus amount of UV exposure as a function of place of residence of the participants at birth and at the time of the study. Children or their parents or guardians responded to a questionnaire about the time they spent outdoors daily at different ages and over the past year.
In the summer before the study, 19% of participants with MS reported spending less than 30 minutes outdoors, compared with 6% of those without MS. And 18% of participants with MS spent one to two hours outdoors, compared to 25% of those without MS.
After adjusting for smoke exposure, gender, and other factors that could affect MS risk, the researchers found that people who spent an average of 30 minutes to an hour outdoors per day during l summer before the study had 52% less risk of MS compared to those who spent an average of less than 30 minutes outdoors per day. Those who spent on average even more time outdoors per day, between one and two hours, were 81% less likely to have MS than those who spent an average of less than 30 minutes per day.
“It’s important to note that too much exposure to the sun without protection also comes with risks, and our study found that spending two or more hours outdoors per day did not further reduce the risk of MS compared to at two o’clock, “Waubant said.
More time spent outdoors in the first year of life was associated with a lower likelihood of MS. The researchers found that location mattered as well. More sunlight where a participant lives was associated with a lower likelihood of MS. For example, researchers estimate that a person living in Florida is 21% less likely to have MS than a person living in New York City.
The study doesn’t prove that sun exposure prevents MS, but it does show an association.
One limitation of the study is that children and their parents or guardians were required to remember sun exposure and sunscreen use from previous years and this recall may not be accurate.
The study was supported by the National Institutes of Health and the National MS Society.
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The American Academy of Neurology is the world’s largest association of neurologists and neuroscientists, with over 36,000 members. The AAN is dedicated to promoting the highest quality patient-centered neurological care. A neurologist is a physician with specialized training in the diagnosis, treatment and management of disorders of the brain and nervous system such as Alzheimer’s disease, stroke, migraine, multiple sclerosis, concussions , Parkinson’s disease and epilepsy.
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