NFL player and mathematics doctoral student John Urschel retired last summer because he was afraid of possible brain damage. He'd had a concussion and found tha

NFL player and mathematics doctoral student John Urschel retired last summer because he was afraid of possible brain damage. He'd had a concussion and found that for some weeks after his ability to think about math was impaired. https://en.wikipedia.org/wiki/John_Urschel https://en.wikipedia.org/wiki/John_Urschel