A hormone the body releases during exercise appears to be a key reason physical activity eases neurological symptoms in multiple sclerosis. In a study published in Nature Metabolism, investigators from Mass General Brigham and University Medical Center Hamburg-Eppendorf tracked levels of irisin in a mouse model of MS and found that the hormone reduced both clinical symptoms and the loss of neurons. When irisin was removed, the protective benefit of exercise vanished as well.
That last detail is what gives the finding its weight. Aerobic exercise has been linked to better outcomes in MS by other research groups, but the biology behind the effect has remained murky. By showing that the benefit disappears without irisin, the researchers make a case that the hormone is not just a bystander but a mechanism through which exercise shields neurons from inflammation-driven damage.
The clinical gap here is real. MS is an autoimmune disease in which the immune system strips the myelin sheaths insulating neurons in the brain and spinal cord, and existing drugs are largely aimed at damping inflammation rather than halting the neurodegeneration that follows. Corresponding author Christiane D. Wrann, who leads the Program in Neuroprotection in Exercise at the Mass General Brigham Neuroscience Institute and the McCance Center for Brain Health, said the team is optimistic the work will push irisin forward as a possible therapy, particularly for progressive MS.
Wrann also framed the result more broadly, arguing it strengthens the case that irisin can protect neurons across multiple types of neurodegenerative disease - a claim of interest to researchers working on Alzheimer's and related conditions. For now, the evidence comes from an experimental mouse model, and translating a hormone target into a human treatment remains the next hurdle.