CTE was first noticed as a “peculiar condition” casually referred to as a “punch-drunk” syndrome in boxers and prizefighters before the 1930s. It was recognized as affecting individuals who took considerable blows to the head, but was believed to be confined to boxers and not other athletes. In 2008, the Sports Legacy Institute joined with the Boston University School of Medicine (BUSM) to form the Center for the Study of Traumatic Encephalopathy (CSTE). Brain Injury Research Institute (BIRI) also studies the impact of concussions.
Between 2008 and 2010, the bodies of twelve former professional American football players underwent postmortem evaluations for CTE, and all of them showed evidence of the disease, indicating a conservatively estimated prevalence rate of 3.7% among professional football players if no other players who died during this period had CTE.
In 2002, Dr. Bennet Omalu, a forensic pathologist and neuropathologist in Pittsburgh, Pennsylvania found CTE in the brains of Mike Webster, Terry Long, Andre Waters, Justin Strzelczyk and Tom McHale. Omalu, in 2012 a medical examiner and associate adjunct professor in California, was a co-founder of BIRI and reportedly in 2012 participated in the autopsy of Junior Seau. Dr. Omalu's participation was halted during the autopsy after Junior Seau's son revoked previously provided oral permission after he received telephone calls from NFL management denouncing Dr. Omalu's professional ethics, qualifications, and motivation.
As of December 2012, thirty-three former National Football League (NFL) players have been diagnosed post-mortem with CTE. Former Detroit Lions lineman and eight-time Pro Bowler Lou Creekmur, former Houston Oilers and Miami Dolphins linebacker John Grimsley, former Tampa Bay Buccaneers guard Tom McHale, former Cincinnati Bengals wide receiver Chris Henry, and former Chicago Bears safety Dave Duerson, have all been diagnosed post-mortem with CTE. Other football players diagnosed with CTE include former Buffalo Bills star running back Cookie Gilchrist and Wally Hilgenberg., among others.
An autopsy conducted in 2010 on the brain of Owen Thomas, a 21-year-old junior lineman at the University of Pennsylvania who committed suicide, showed early stages of CTE, making him the second youngest person to be diagnosed with the condition. Thomas was the second amateur football player diagnosed with CTE, after Mike Borich, who died at 42. The doctors who performed the autopsy indicated that they found no causal connection between the nascent CTE and Thomas's suicide. There were no records of Thomas missing any playing time due to concussion, but as a player who played hard and "loved to hit people," Thomas may have played through concussions and received thousands of subconcussive impacts on the brain.
In October 2010, 17-year-old Nathan Stiles died hours after his high school homecoming football game, where he took a hit that would be the final straw in a series of subconcussive and concussive blows to the head for the highschooler. The CSTE diagnosed him with CTE, making him the youngest reported CTE case to date.
In July, 2011, Colt tight end John Mackey died after several years of deepening symptoms of frontotemporal dementia. BUSM was reported to be planning to examine his brain for signs of CTE. The CSTE found CTE in his brain post-mortem.
In 2012, retired NFL player Junior Seau committed suicide with a gunshot wound to the chest. There was speculation that he suffered brain damage due to CTE. Seau's family donated his brain tissue to the National Institute of Neurological Disorders and Stroke. On January 10, 2013, the brain pathology report was revealed and Seau did have evidence of CTE.
On July 27, 2012, an autopsy report concluded that the former Atlanta Falcons safety Ray Easterling, who committed suicide in April 2012, had CTE.
The NFL has taken measures to help prevent CTE. As of July 2011, the NFL has changed its return-to-play rules. The number of contact practices has been reduced, based on the recent collective bargaining agreement.
In 2012, some four thousand former NFL players "joined civil lawsuits against the League, seeking damages over the League’s failure to protect players from concussions, according to Judy Battista of the [New York] Times".
On August 30, 2013, the NFL reached a $765 million settlement with the former NFL players over the head injuries. The settlement created a $675 million compensation fund from which former NFL players can collect from depending on the extent of their conditions. Severe conditions such as Lou Gehrig's disease and postmortem diagnosed chronic traumatic encephalopathy would be entitled to payouts as high as $5 million. From the remainder of the settlement, $75 million will be used for medical exams, and $10 million will be used for research and education. However, in January, 2014, U.S. District Judge Anita B. Brody refused to accept the agreed settlement because "the money wouldn't adequately compensate the nearly 20,000 men not named in the suit".
Bernie Kosar, who sustained several concussions during his twelve-year NFL career and has shown symptoms of CTE, has submitted himself to an experimental treatment program led by Dr. Rick Sponaugle of Florida that has alleviated many of his symptoms. The program, the details of which are proprietary, involves increasing blood flow to damaged portions of the brain. He has spoken out in public about his successes with the treatment in the hopes that others who suffer from the disease can find relief and avoid the fates of Duerson and Seau, both of whom were personal friends of Kosar's. The efficacy of Dr. Sponaugle's treatment has not been validated through any published clinical trials or other validated scientific process, nor has this treatment been supported by any reputable medical group conducting research into CTE.