There are concerns about the consequences that exposure to head injuries can lead to neurodegenerative illnesses, specifically chronic traumatic encephalopathy (CTE). This illness has been found to create cognitive, psychiatric, and behavioral problems (traumatic encephalopathy syndrome [TES]). CTE has been traced back to boxing as a consequence of repeated head injuries. Based on the National Institute of Neurological Disorders and Stroke, the criteria needed for TES include having significant exposure to repeated head impacts, cognitive impairments, neurobehavioral dysregulation, a progressive course, and a lack of explanation for another illness. Some studies are necessary to support or go against the idea that head impacts lead to CTE and that there are clinical signs or symptoms to look out for. However, this has become more prominent in American football players.