Chronic Traumatic Encephalopathy (CTE)

Chronic traumatic encephalopathy (CTE) is a gradually progressing disease of the brain that occurs most frequently in athletes and other individuals who have experienced repeated blows, including concussions, to the head. The condition first became known in the 1920s as a disease affecting boxers. Additional cases mostly involving athletes were reported over the following decades, but broad recognition of CTE did not occur until the early 2000s when it made headlines after being discovered in a deceased professional football player in the United States. In CTE, repetitive brain trauma sparks a progressive degeneration of brain tissue and an excessive build-up of a protein called tau that can occur over months, years, or even decades. The progression continues even after the trauma incidents have stopped, leading to potential memory loss, confusion, depression, aggression, impaired judgment, problems with impulse control, and dementia.

Brief History

CTE was initially dubbed dementia pugilistica, or “punch drunk syndrome,” when it was first described in the 1920s as a condition that afflicted a group of boxers. A smattering of similar cases was reported in the subsequent years. In the 1960s, the name for the condition was changed to chronic traumatic encephalopathy, but it was still largely considered to be a disease of the boxing community. That view changed in 2002 when a neuropathologist named Bennet Omalu documented and published the first evidence of CTE in a football player, American Hall of Famer Mike Webster of the Pittsburgh Steelers. Webster was only fifty years old at the time of his death, but his brain was ravaged by the toll CTE had taken over the years as a result of contact injuries suffered during his career on the field.

Since then, CTE has been diagnosed postmortem in several cases that garnered significant media attention, including the suicide deaths of National Football League (NFL) player Junior Seau and professional wrestler Chris Benoit, who hanged himself after killing his wife and son in a violent act of aggression. Debilitating depression and unchecked aggression are both common symptoms of late-stage CTE.

As a CTE-afflicted brain slowly degenerates, it will lose vital mass. As that happens, some areas of the brain are likely to atrophy while others are more apt to enlarge. Some areas of the brain will also undergo a build-up of tau protein, which is a molecule that traditionally steadies cellular structure in the neurons. However, if tau protein becomes unbalanced or defective due to CTE, it can cause substantial interference with neuron function, inhibiting normal brain behavior and response.

Overview

The symptoms of CTE can be incapacitating for those affected and may dramatically alter the lives of both the person with CTE and that person’s family and friends.

Some of the most frequently experienced symptoms of CTE are loss of memory, struggling to control impulsive and erratic behavior, impaired judgment, depression and aggression, problems with balance, and eventual signs of dementia. As the disease is still being studied and is often complicated to diagnose, some of the symptoms of CTE are often presumed to be part of the normal process of aging, or sometimes CTE is incorrectly diagnosed as other neurological disorders, such as Alzheimer’s disease or Parkinson’s disease.

As of 2022, CTE can only be diagnosed after death, during an autopsy examination of the brain. Funded by a grant from the Brain Injury Research Institute, the University of California in Los Angeles has embarked on research that may discover a means for diagnosing CTE in living patients. The idea is to use a biomarker to detect tau protein concentrations as a way to identify CTE among the living. Other institutions have also set up centers, such as the prominent site at Boston University (BU), dedicated, in part, to studying a method for determining evidence of CTE in living people, particularly through the use of magnetic resonance imaging (MRI). Diagnostic testing that can help identify potential CTE at its early stages would mean that it could be possible to screen professional athletes, military personnel, and other susceptible individuals who are at risk for developing CTE to safeguard them against further injury and help them to be proactive in identifying symptoms and dealing with the progressive disease. Eventually, research aims to find ways to cure CTE, but for now the focus is on early detection.

Widespread concerns about head injuries and their association with the progressive degenerative disease of CTE have placed greater scrutiny and onus on contact sports. Under pressure, the NFL finally issued an official acknowledgement in March 2016 recognizing that there is an indisputable link between CTE and head trauma sustained in football. The NFL had been denying the connection for years despite the numerous players in whom CTE was discovered during autopsy. According to some estimates, the incidence of CTE in professional football players may be as high as 90 percent. A study published in the Journal of the American Medical Association (JAMA) in 2017 examined the brains of 111 deceased NFL players and found that 110 had CTE. The JAMA study was the largest of its kind that had been conducted at that time. In January 2018, Washington State University quarterback Tyler Hilinski died by suicide at the age of twenty-one. After his death, Hilinski’s family agreed to give his brain to Minnesota’s Mayo Clinic for an autopsy. The autopsy revealed that Hilinski had CTE at the time of his death. According to the medical examiner, Hilinski’s brain looked like that of a sixty-five-year-old due to the condition.

Cases of the potentially tragic effects of CTE continued into the 2020s. After performing an autopsy on former NFL player Phillip Adams, who had killed himself following a period on a day in April 2021 during which he shot and killed six people, experts reported finding a level of CTE that had been atypical in its severity. In December of that year, an autopsy report of former NFL wide receiver Vincent Jackson, who had been discovered dead in a hotel room in February, indicated that the direct cause of his death had been chronic alcohol use. At the same time, his brain showed signs of Stage 2 CTE, which physicians and his family speculated had likely contributed in a major way to his abuse of alcohol. Additionally, BU's CTE Center released findings that same December from a large study conducted to determine the risk of football players developing amyotrophic lateral sclerosis disease (ALS), which had been tentatively connected with CTE. According to their results, NFL players have a four-times higher chance of developing and dying from ALS than the overall adult male population.

At the same time, CTE is not confined to football or boxing. Anyone who plays a rigorous sport that involves repeated or significant contact to the head is at risk, as are individuals who engage in activities or professions with high likelihood of head trauma. A number of professional ice hockey players have been diagnosed with CTE postmortem or have exhibited symptoms of the disease; this is particularly common in enforcers, or players who have a record of fighting on the ice. Some professional athletes from the ranks of racing, soccer, baseball, football and wrestling have announced to the press that they intend to donate their brains after death to aid in the research toward diagnosing and eventually treating CTE.

In the 2010s and early 2020s, new research linked CTE development to an even wider range of athletic activities. Some athletes who played sports not known for their violent or high–contact nature, such as baseball, were found to have symptoms of the disease. In 2014, for example, researchers at BU revealed that they had diagnosed a deceased former soccer player with Stage 2 CTE. Researchers identified the practice of "heading" the ball, or hitting the ball with one's head, as a particular risk factor for CTE development in soccer players. In 2023 an Australian rules football player named Heather Anderson, who had died by suicide the year before. Although other women had previously been diagnosed with the disease after their deaths, Anderson was the first female professional athlete to be diagnosed with CTE.

Other sports, such as hockey, also came under greater scrutiny during this time. While researchers had already found CTE in a number of hockey players known for being enforcers, new research began to identify the presence of CTE in "skill" players not known for frequent fighting or physical contact on the ice. For example, in February 2022, researchers at BU studying the body of Ralph Backstrom, a former professional hockey player who spent years playing in the National Hockey League (NHL), diagnosed him with Stage 3 CTE. These findings highlighted the possibility of CTE development in athletes not known for engaging in particularly physical behavior, as well as the risk of CTE development in sports not typically considered violent or dangerous. Based on the cases of Backstrom and other hockey players, researchers at BU hypothesized that each additional year playing ice hockey could increase the risk of CTE development by as much as 23 percent.

Bibliography

Abrams, Jonathan. "Phillip Adams Had Severe C.T.E. at the Time of Shootings." The New York Times, 14 Dec. 2021, www.nytimes.com/2021/12/14/sports/football/phillip-adams-cte-shootings.html. Accessed 25 Jan. 2022.

Belson, Ken. "'It's Not the Ending He Wanted.'" The New York Times, 16 Dec. 2021, www.nytimes.com/2021/12/16/sports/football/vincent-jackson-death-cte.html. Accessed 25 Jan. 2022.

Bien, Louis. “Why the NFL Can Finally Admit Football Causes CTE and Not Owe Players Anything.” SB Nation. Vox Media, 18 Apr. 2016. Web. 4 Aug. 2016.

Branch, John. "Brain Trauma Extends to the Soccer Field." The New York Times, 26 Feb. 2014, www.nytimes.com/2014/02/27/sports/soccer/researchers-find-brain-trauma-disease-in-a-soccer-player.html. Accessed 11 Apr. 2022.

Catanese, Lisa. "What is CTE? Understanding Chronic Traumatic Encephalopathy." Harvard Health Publishing, 28 Mar. 2024, www.health.harvard.edu/mind-and-mood/what-is-cte-understanding-chronic-traumatic-encephalopathy. Accessed 25 Jul. 2024.

HealthDay News. "More Years Playing Hockey, Higher Odds for CTE Linked to Head Injury." U.S. News & World Report, 3 Mar. 2022, www.usnews.com/news/health-news/articles/2022-03-03/more-years-playing-hockey-higher-odds-for-cte-linked-to-head-injury. Accessed 11 Apr. 2022.

Hernandez, Joe. "NFL Players Are 4 Times More Likely to Develop ALS, a New Study Shows." NPR, 16 Dec. 2021, www.npr.org/2021/12/16/1064850108/nfl-players-als-study. Accessed 25 Jan. 2022.

Mather, Victor. "C.T.E. Found for First Time in Female Pro Athlete." The New York Times, 4 Jul. 2023, www.nytimes.com/2023/07/04/sports/cte-female-athlete-heather-anderson.html. Accessed 25 Jul. 2024.

McKee, Ann C., et al. “Chronic Traumatic Encephalopathy in Athletes: Progressive Tauopathy after Repetitive Head Injury.” Journal of Neuropathology and Experimental Neurology 68.7 (2009): 709–35.

Mez, Jesse, et al. “Clinicopathological Evaluation of Chronic Traumatic Encephalopathy in Players of American Football.” Journal of the American Medical Association, vol. 319, no. 4, 2017, pp. 360–70.

Petraglia, Anthony L., Julian E. Bailes, and Arthur L. Day. Handbook of Neurological Sports Medicine: Concussion and Other Nervous System Injuries in the Athlete. Champaign: Human Kinetics, 2015.

Reddy, Luke. “Larry Johnson: Ex-NFL Player on Battle with What He Thinks Is Chronic Traumatic Encephalopathy.” BBC Sport, 15 Dec. 2017, www.bbc.com/sport/american-football/42364622. Accessed 3 Jan. 2018.

Stump, Scott. “Parents of College Quarterback Tyler Hilinski Reveal Son Had CTE When He Died by Suicide.” Today, 26 June 2018, www.today.com/health/college-football-player-tyler-hilinski-who-died-suicide-had-cte-t131843. Accessed 9 July 2018.

Welch, Ashley. “Report: Brain Disease CTE Found in 87 Deceased NFL Players.” CBS News. CBS Interactive, 18 Sept. 2015. Web. 4 Aug. 2016.

“What Is CTE?” Brain Injury Research Institute. Brain Injury Research Inst., n.d. Web. 4 Aug. 2016.

Yong, Ed. “The Science of Head Trauma.” Scientist. Scientist, 13 Mar. 2013. Web. 4 Aug. 2016.

Zollman, Felise S. Manual of Traumatic Brain Injury: Assessment and Management. 2nd ed. New York: Demos Medical, 2016.