Detailed scans of concussed University of British Columbia hockey players found that the protective fatty tissue surrounding brain cell fibers was loosened two weeks after the injury—even though the athletes felt fine and were deemed ready to return to the ice. A loosening of that insulation, called myelin, slows the transmission of electrical signals between brain cells, or neurons. Researchers have previously shown in animals that this loosened myelin can completely deteriorate with subsequent blows—a condition that resembles the neurodegenerative disease multiple sclerosis.
