According to the Centers for Disease Control (CDC) concussions due to sports participation are increasing annually in the United States. It is estimated that between 10 to 20 percent of pro and recreational football players may have a concussions in any given year. Football injuries associated with a head injury happen in one in every three and a half games. The study titled "Recurrent Sport-Related Concussion Linked to Clinical Depression" found a cumulative effect of concussions. The neurological consequences of mild traumatic brain injuries have been shown to be greater than previously thought
Studies have shown that nearly two-thirds of players sustained at least one concussion during their professional career, and a quarter sustained three or more concussions in their career. The average number of concussions during an NFL football career is an estimated to be at least two
Source: American Association of Neurological Surgeons