A short protein fragment, or peptide, may lead the way to healing traumatic brain injuries, a primary cause of death and disability among youth. Currently, drugs to treat such injuries are injected directly into the brain — an invasive technique — or into the bloodstream, which allows the medication to spread throughout the brain, causing harmful side effects. Attaching drugs to the new peptide, called CAQK, would avoid these problems. The peptide, just four amino acids long, bind…