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NFL Football & Chronic Traumatic Encephalopathy (CTE): An Overview

NFL Football & Chronic Traumatic Encephalopathy (CTE): An Overview

Authors: Somil Bhushan, Simon Jiang

The National Football League (NFL) represents an organized form of sports that was created in America and symbolizes a core component of social culture. For many people, football is more than just a game – it’s a way to connect with others and express their love for their team or country (Intelligencer, 2023). Football was originally just a pastime during the late 19th century in North America. Since then, it has grown into one of the most beloved sports on the continent. It has inspired countless books and movies about teams, players, and coaches that have left an indelible mark on American [society] (Intelligencer, 2023). Professional football has greatly helped bring communities closer together by providing a common interest that can be shared by people from all walks of life. It has provided an avenue for athletes to make a living while pursuing their dreams of playing at the highest level (Intelligencer, 2023). However, one common distinction of football that separates it from many other sports is the aggression it entails through tackling, collisions, and head-to-head contact. While these hallmarks of the sport provide widespread entertainment for the fans who come to support and watch their teams, it raises concerns for the health and well-being of the individual players on the field. As injury prevention is a priority for the NFL while maintaining the same high-intensity persona of the sport, rules have been changed over time involving the manner in which players may tackle and hit one another. Despite these precautions, players who have been involved with the league for multiple years beforehand and have incurred head-to-head contact may pose a risk for a specific adverse health outcome known as chronic traumatic encephalopathy (CTE).

CTE is a progressive and fatal brain disease associated with repeated traumatic brain injuries (TBIs), including concussions and repeated blows to the head. Figure 1 highlights the physiological effects of concussions inside the brain. CTE is also associated with the development of dementia (Association, 2023). Those at greatest risk for CTE are athletes who play contact sports (e.g., boxers, football players, etc.) and military veterans, likely due to their increased chances of enduring repeated blows to the head (Association, 2023). Research on CTE diagnosis, cause(s), symptoms, and risk factors is still in the early stages. Physiologically, brains with CTE have a buildup of a protein known as tau around the blood vessels (Clinic, 2023). Tau buildup in CTE is different from accumulations of tau found in Alzheimer's disease and other forms of dementia (Clinic, 2023). Figure 2 reveals images from a case study of a former football player with severe CTE whose brain was examined and stained for the presence of tau protein indicated by brown coloring. CTE is thought to cause atrophy. This happens because injuries to nerve cells that conduct electrical impulses affect communication between cells (Clinic, 2023). Not all scientists agree on the symptoms of CTE, but the disease has been associated with memory and thinking problems, confusion, personality changes, and/or erratic behavior including aggression, depression, and even suicidal thinking (Association, 2023). In addition, other symptoms may include problems paying attention and organizing thoughts, as well as difficulty with balance and motor skills. People may not experience these potential signs of CTE until years or decades after brain injuries occur (Association, 2023). CTE symptoms don't develop right after a head injury (Clinic, 2023). Experts believe that they develop over years or decades after repeated head trauma. Moreover, it is thought that CTE symptoms appear in two forms (Clinic, 2023). In early life between the late 20s and early 30s, the first form of CTE may cause mental health and behavioral issues. Symptoms of this form include depression, anxiety, impulsive behavior, and aggression (Clinic, 2023). The second form of CTE is thought to cause symptoms later in life, around age 60. These symptoms include memory and thinking problems that are likely to progress to dementia (Clinic, 2023).

Figure 1: Concussions & The Brain (Clinic, 2023)

 Figure 2: Case Study of Brain with Severe CTE Stained for Tau Protein (Sciences, 2017)

Diagnosing CTE is complicated in terms of allowing for early detection of the health issue. This is because there is currently no way to definitively diagnose CTE during life (Clinic, 2023). Although, experts have developed clinical criteria for traumatic encephalopathy syndrome (TES) (Clinic, 2023). TES is a clinical disorder associated with CTE. It can only be suspected in people who are at high risk due to repeated head trauma over years during sports or military experiences (Clinic, 2023). A diagnosis requires evidence of degeneration of brain tissue and deposits of tau and other proteins in the brain (Clinic, 2023). This can only be seen after death during an autopsy (Clinic, 2023).  Figure 3 highlights the physical differences between a normal brain and a brain with CTE. Researchers are actively trying to find a test for CTE that can be used while people are alive. Others continue to study the brains of deceased individuals who may have had CTE, such as U.S. football players. The hope is to eventually use neuropsychological tests, brain imaging such as specialized MRIs, and other biomarkers to diagnose CTE (Clinic, 2023). Moreover, there is no treatment for CTE (Clinic, 2023). The brain disorder is progressive, which means it continues to get worse over time (Clinic, 2023). More research on treatments is needed, but the current approach is to prevent head injury. It's also important to stay informed about how to detect and manage traumatic brain injury (Clinic, 2023). 

Figure 3: What CTE Looks Like in the Brain (Sciences, 2017)

CTE was found in the brains of over 320 former NFL players, and undetected cases likely exist in live players and players who were buried without an analysis. Autopsies have found CTE in the brains of former professional players such as Junior Seau (Chargers), Aaron Hernandez (Patriots), and Jovan Belcher (Chiefs), who were all found dead by suicide. CTE brings with it impairment in decision-making and worsens rage and aggression, which may increase chances of committing violent crime. A study conducted by Boston University found CTE in 91.7% of the NFL players’ brains they studied. This is only one study and the examined sample may not be representative of the NFL as a whole, but the statistic is still jarring enough to demand action.

The fact that the disease is impossible to diagnose in a live player means we simply don’t know the full number of players affected by CTE - chances are, there are players in the NFL carrying cases of CTE that we have no way to discover. While with cancer patients we can detect tumors then offer treatment to individuals before it worsens, we can’t administer CTE-specific drugs because we can’t diagnose the disease. This means - until a method of live diagnosis is developed - actions to fight CTE must be preventative rather than reactionary, and decisions must be made at the administrative level of the NFL since doctors are powerless to provide targeted therapies for the disease. 

In a step forward, a recent NFL policy has closed a loophole that allowed for concussed players to return to the playing field shortly after sustaining a serious injury. This loophole allowed for scenes such as a player, concussed to the point of being barely able to walk, returning to the field only minutes later. The NFL has also added doctors and neuro-trauma specialists to the sidelines of each game. Repeated concussions are suspected to instigate CTE development, so these policy changes alleviate a major suspect cause of the disease. The difficult part of CTE policy is that it is impossible to immediately judge effectiveness because of CTE’s elusiveness. With current methods, it will be impossible to measure whether the NFL’s changes actually decrease CTE cases until years, possibly decades later; even then the data set will not be complete since not all players’ families will consent to diagnoses. 

CTE is one of the most terrifying diseases plaguing football, being elusive enough to remain undetected while being severe enough to destroy players’ wellbeing and tear lives apart. While it is possible to decrease CTE rates by policy changes within the NFL, it will be impossible to gauge efficacy in a reasonable time period until it becomes possible to diagnose CTE in live players. Measuring the effectiveness of CTE policy without a method of live diagnosis will be as difficult as judging a president without being able to track their country’s economic growth. Further research and funding is needed to develop a CTE diagnosis performable on live players, and once the disease is made more detectable, targeted interventions will become a possibility. 


Battista, Judy. “Changes Coming to NFL Concussion Protocol a Needed Step for Player Safety.” NFL.Com, NFL, 2 Oct. 2022,

Clinic, M. (2023). Chronic traumatic encephalopathy—Symptoms and causes. Mayo Clinic.

Intelligencer. (2023, September 29). Nfl: Understanding the social significance of america’s favorite sport. Theintelligencer.Net.

Kilgore, Adam. “Aaron Hernandez Suffered from Most Severe CTE Ever Found in a Person His Age - The Washington Post.” Washington Post, The Washington Post, 9 Nov. 2017,

Mann, Denise. “In Autopsy Study, Over 90% of Former NFL Players Showed Signs of Brain Disease CTE.” U.S. News, U.S. News, 9 Feb. 2023,

Sciences, L. (2017, July 25). Images: Brains with cte. Livescience.Com.

Shpigel, Ben. “What to Know About C.T.E. in Football.” The New York Times, The New York Times, 5 July 2022,



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