Mass General Brigham May 21 2026 A new study offers clues as to why exercise can improve neurological symptoms in people with multiple sclerosis (MS). The study, led by investigators from Mass General Brigham and University Medical Center Hamburg-Eppendorf (UKE), examined levels of the exercise hormone irisin in a mouse model of multiple sclerosis. Researchers found that irisin reduced both clinical symptoms and the loss of neurons in the experimental model. Additionally, when irisin was