Researchers at University College London have discovered early blood markers (excess cytokines–signaling proteins–a sign of an overly aggressive immune system) in people with the gene for Huntington’s disease, a neurodegenerative disorder .

These markers show that the neurodegeneration may start more than 15 years before neurological symptoms are apparent. People with the Huntington’s mutation typically first experience symptoms in their 30s or 40s, and live an average of 15 to 20 years after that. Researchers speculate that the cytokines (released by immune cells in the brain called microglia) may be killing–or contributing to the death of–healthy neurons.

If cells that release excessive cytokines could be kept at bay, the progression of the disease could be slowed down. Measured cytokine levels could be a way to test the effectiveness of new treatments for Huntington’s.