Former NFL quarterback Dan Marino has withdrawn from a suit against the NFL. The suit says the league knew for years there was a link between concussions and long-term health problems. Scientists believe repeated head trauma can cause chronic traumatic encephalopathy, or CTE, a progressive degenerative disease of the brain. Symptoms include depression, aggression, and disorientation, but so far scientists can only definitively diagnose it after death. Here are a few of the former athletes who have been diagnosed with CTE.