Studies untangle dark and light sides of immune disorder
Darkness and light may help prevent multiple sclerosis or fend off its symptoms.
People who genetically produce less vitamin D, a compound normally boosted by sun exposure, have a greater risk of multiple sclerosis, researchers find. But the hormone melatonin, which the body produces in response to darkness, may reduce flare-ups for people who have the disease, another team of scientists reports.
The studies may help researchers better understand and treat multiple sclerosis, a disease of the nervous system. It causes symptoms including muscle weakness, pain and vision loss in over 2 million people worldwide.
Previous studies linked lower vitamin D levels to higher multiple sclerosis risk, but it was unclear whether this relationship was a coincidence. In work appearing August 25 in PLOS Medicine, scientists examined genetic data from thousands of Europeans and found that three genetic changes known to reduce vitamin D levels