Images of a Hard-Hitting Disease

It is estimated [1] that football players can receive as many as 1,500 hits to the head in one season. Not every blow results in immediate injury, but a growing body of research suggests that repetitive hits can lead to serious, long-term brain damage. More than 20 NFL players have so far been diagnosed with chronic traumatic encephalopathy (CTE), a neurodegenerative disease, after their deaths.

SOURCE [2]