WE’VE known since 1964 that cigarette smoking is harmful to your health. We’ve known for more than 40 years that alcohol damages the developing brain of a child. We’ve known since the mid 70's that asbestos causes cancer and other serious diseases. Knowing what we know now, we do not smoke in enclosed public spaces like airplanes; we have passed laws to keep children from smoking or drinking alcohol; and we do not use asbestos as an industrial product. As we become more intellectually sophisticated and advanced, with greater and broader access to information and knowledge, we have given up old practices in the name of safety and progress. That is, except when it comes to sports. Over the past two decades it has become clear that repetitive blows to the head in high impact contact sports like football, ice hockey, mixed martial arts and boxing place athletes at risk of permanent brain damage. There is even a Hollywood movie, “Concussion,” that dramatizes the story of my discoveries in this area of research.