Chronic traumatic encephalopathy, or CTE, is a degenerative brain disease linked to repeated head trauma. The condition first gained attention in high-impact sports, such as football and boxing, but it has since been linked to a range of activities in which people sustain repetitive brain injuries, such as cycling and military service.
CTE was first defined in 1949 by neurologist Dr. MacDonald Critchley, but there's still a lot scientists don't know about it. For instance, it's unclear how to diagnose the disease in living patients, or if certain environmental or genetic factors raise the risk of a person developing it, according to the Centers for Disease Control and Prevention (CDC).
