What’s less clear is how to fix the problem. Even impacts that don’t directly affect the head may cause microscopic damage or initiate toxic processes that unfold over time, and current therapies for concussion and head impacts tend to address symptoms, like headache and balance issues, that can arise well after the initial injury.

But an unorthodox treatment called near-infrared light therapy, which shines powerful near-infrared light at the brain through the skull, may be able to prevent or reduce subtle damage to the brain before symptoms start, by reducing brain inflammation caused by repetitive impacts.

A preliminary study with 26 collegiate football players suggests that the therapy could significantly protect players’ brains from inflammation over the course of a football season.