A new study has found direct evidence that an over-the-counter antihistamine can repair the protective nerve sheath that's damaged in people with multiple sclerosis. The researchers also identified a biomarker that can be used to measure the drug's effectiveness, opening the door to a potential new treatment for the debilitating disease. In the autoimmune disease multiple sclerosis (MS), the body's immune system attacks the protective myelin sheath that covers nerves, causing irreversible damage and disrupting communication between