Research from Washington University School of Medicine in St. Louis reveals how brain inflammation triggers extreme muscle weakness across several diseases, including viral infection, bacterial infection and Alzheimer’s disease. Shown are fruit fly muscles; the violet staining is a measure of how well mitochondria in muscle cells are producing energy. On the left is a healthy muscle, and on the right is a muscle exposed to IL-6, an immune-related molecule produced by the brain in response to infections or chronic disease.