(CNN)Here's a look at concussions in the National Football League. A concussion is a type of traumatic brain injury caused by a blow to the head.
Reports show an increasing number of retired NFL players who have suffered concussions have developed memory and cognitive issues such as dementia, Alzheimer's, depression and chronic traumatic encephalopathy (CTE). CTE is a degenerative disease of the brain and is associated with repeated head traumas.
Common Symptoms of Concussions
(The NFL Player Concussion Pamphlet)
Imbalance
Headache
Confusion
Memory loss
Loss of consciousness
Vision change
Hearing change
Mood change
Fatigue
Malaise
Imbalance
Headache
Confusion
Memory loss
Loss of consciousness
Vision change
Hearing change
Mood change
Fatigue
Malaise
Statistics on Diagnosed Concussions
(NFL and IQVIA)
(Preseason and regular-season practices plus games)
(Preseason and regular-season practices plus games)
2015 - 275
2016 - 243
2017 - 281
2018 - 214
2019 - 224
2020 - 172 (no preseason games due to the Covid-19 pandemic)
2021 - 187
2022 - 213
Timeline
1994 - In response to a series of player retirements due to head injuries, including the retirement of Chicago Bears fullback Merril Hoge due to repeated concussions, NFL Commissioner Paul Tagliabue creates the Mild Traumatic Brain Injury Committee. Dr. Elliot Pellman is named chairman despite not having experience with brain injuries.
2002 - Dr. Bennet Omalu, a forensic pathologist and co-founder of the Brain Injury Research Institute, identifies CTE in the brain of former Pittsburgh Steelers' center Mike Webster, 50, who died by suicide. Omalu is the first to identify CTE in American football players.
January 2005 - The NFL's Mild Traumatic Brain Injury Committee finds that returning to play after sustaining a concussion "does not involve significant risk of a second injury either in the same game or during the season."
2005 and 2006 - Dr. Omalu identifies CTE in the brains of former Pittsburgh Steelers players Terry Long and Andre Waters. Both died by suicide.
February 2007 - Dr. Pellman steps down as chairman of the Mild Traumatic Brain Injury Committee but remains a member.
August 14, 2007 - The NFL formalizes new concussion guidelines which include a telephone hotline to report when a player is being forced to play contrary to medical advice.
October 28, 2009 - Part I of the House Judiciary Committee hearing on Legal Issues Relating to Football Head Injuries. NFL Commissioner Roger Goodell defends the League's policy regarding concussions.
January 4, 2010 - Part II of the House Judiciary Committee hearing on Legal Issues Relating to Football Head Injuries. Dr. Ira Casson, one of the co-chairs of the Mild Traumatic Brain Injury Committee, denies a link between repeat head impacts and long-term brain damage.
March 2010 - The NFL's Mild Traumatic Brain Injury Committee is renamed the Head, Neck and Spine Committee. Two new co-chairs are selected, and Dr. Pellman is no longer a member of the panel.
October 20, 2010 - Goodell issues a memo to all teams that warns of possible suspensions for "violations of the playing rules that unreasonably put the safety of another player in jeopardy." He says this "is especially true in the case of hits to the head and neck."
February 17, 2011 - Former Chicago Bears defensive back Dave Duerson, 50, kills himself with a gunshot wound to the chest rather than his head so his brain can be researched for CTE. Boston University researchers find CTE in Duerson's brain.
August 17, 2011 - A class action lawsuit against the NFL over concussion-related injuries is filed by former players. Former Atlanta Falcons safety Ray Easterling is listed as the lead plaintiff. On April 19, 2012, Easterling, 62, dies by suicide. An autopsy finds signs of CTE.
May 2, 2012 - Former NFL linebacker Junior Seau, 43, is found dead with a gunshot wound to the chest, classified as suicide. On January 10, 2013, the NIH releases the results of their analysis of Seau's brain tissue confirming that Seau did suffer from CTE. Seau's family files a wrongful death lawsuit against the NFL on January 23, claiming that Seau's suicide was the result of a brain disease caused by violent hits he endured while playing the game. On October 5, 2018, Seau's family reaches a confidential settlement agreement with the NFL.
June 7, 2012 - A unified lawsuit combining more than 80 concussion-related lawsuits on behalf of more than 2,000 National Football League players is filed in federal court in Philadelphia. The players accuse the NFL of negligence and failing to notify players of the link between concussions and brain injuries. The NFL and ex-players reach a deal in the lawsuit that calls for the NFL to pay $765 million to fund medical exams, concussion-related compensation, medical research for retired NFL players and their families, and litigation expenses, according to a court document filed on August 29, 2013. On January 14, 2014, a federal judge declines to approve the proposal, saying she doesn't believe sufficient evidence had been produced to show that the settlement was adequate. Final approval in the lawsuit settlement is given on April 22, 2015. The agreement provides up to $5 million per retired player for serious medical conditions associated with repeated head trauma.
September 5, 2012 - The Foundation for the National Institutes of Health announces the NFL has committed to donating $30 million to support research on medical conditions prominent in athletes.
December 13, 2013 - The body of former NFL linebacker Jovan Belcher is exhumed in order to perform tests on his brain, a lawyer for the player's family tells the Kansas City Star. On December 1, 2012, Belcher, 25, shot his longtime girlfriend to death and then killed himself. Dr. Piotr Kozlowski releases a report on Belcher on September 30, 2014, stating that he likely had CTE when he killed his girlfriend and himself.
November 25, 2015 - Frank Gifford's family says he suffered from CTE. Gifford's diagnosis comes amid a growing focus on the risks athletes face from suffering repeated concussions, and just hours after the NFL admitted its concussion protocols had failed when St. Louis Rams quarterback Case Keenum kept playing Sunday even after his head injury on the field.
March 14, 2016 - For the first time, a senior NFL official publicly acknowledges a connection between football and CTE. At a round-table discussion with the US House Committee on Energy and Commerce, when asked if "there is a link between football and degenerative brain disorders like CTE," Jeff Miller, the NFL's senior vice president of health and safety policy, answers "the answer to that question is certainly, yes."
July 25, 2016 - The NFL and NFL Players' Association (NFLPA) implement a new policy to enforce concussion protocol. Teams violating the policy are subject to discipline, through fines or losing upcoming draft picks.
September 14, 2016 - Goodell announces an initiative intended to increase the safety of the game, specifically by preventing, diagnosing and treating head injuries. As part of the initiative, the league and its 32 club owners will provide $100 million in support of engineering advancements and medical research -- in addition to the $100 million previously pledged by the league to medical and neuroscience research.
July 25, 2017 - A study published in the medical journal JAMA identifies CTE in 99% of deceased NFL players' brains that were donated to scientific research -- 110 out of 111 former NFL players.
September 21, 2017 - Attorney Jose Baez tells reporters that results from tests performed on the brain of Aaron Hernandez, the former New England Patriots tight end who was convicted in 2015 of murder, showed a "severe case" of CTE. The conviction was vacated after Hernandez's death in April 2017.
November 10, 2017 - Researchers publish in the journal Neurosurgery what they say is the first case of a living person identified with CTE. Lead author Dr. Omalu confirms to CNN that the subject of the case, while unnamed in the study, was former NFL player, Fred McNeill -- who died in 2015. The only way to definitively diagnose CTE is with a brain exam after death.
September 12, 2019 - The NFL announces that a total of $3 million has been made available in the "NFL Helmet Challenge," including $2 million in grant funding to support the development of a helmet prototype and a further $1 million prize for the winner.
August 25, 2020 - Two retired players, Kevin Henry and Najeh Davenport, file a lawsuit against the NFL for allegedly discriminating against Black players who submitted dementia-related claims in the concussion settlement.
June 2, 2021 - The NFL pledges to end "race-norming," a controversial practice that assumes Black players start with a lower level of cognitive brain function than other White and non-Black players, and to review previous test scores for bias in the settlement payout qualification process.
March 4, 2022 - A federal judge approves modifications to the NFL's concussion agreement settlement to end the use of race norms and demographic estimates based on race for scoring of diagnostic tests.
October 8, 2022 - The NFL and NFLPA agree to update the league's concussion protocol, after a review of the response to Miami Dolphins quarterback Tua Tagovailoa's injury on September 25. Under the new protocol, players will be unable to compete if they are experiencing ataxia, which describes a lack of coordination caused by poor muscle control.
February 6, 2023 - The Boston University CTE Center announces that they have diagnosed CTE in 91.7% of former NFL players they have studied -- 345 out of 376 former players.
Photos: Athletes and CTE
Former pro football player Kevin Turner, shown here during a 1998 NFL game, had the most advanced stage of CTE when he died in March at the age of 46. Dr. Ann McKee of Boston University and the Concussion Legacy Foundation said that Turner's CTE brought on amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease.
CTE stands for chronic traumatic encephalopathy, a neurodegenerative disease associated with repeated head trauma. Scientists believe repeated head trauma can cause CTE, a progressive degenerative disease of the brain. Symptoms include depression, aggression and disorientation, but scientists can definitively diagnose it only after death.
CTE stands for chronic traumatic encephalopathy, a neurodegenerative disease associated with repeated head trauma. Scientists believe repeated head trauma can cause CTE, a progressive degenerative disease of the brain. Symptoms include depression, aggression and disorientation, but scientists can definitively diagnose it only after death.
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Photos: Athletes and CTE
BMX star Dave Mirra, who was found dead of a self-inflicted gunshot in February, was found to have CTE.
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Photos: Athletes and CTE
Charles "Bubba" Smith, a former football player and actor who died in 2011, was also diagnosed with CTE. Smith played for the Baltimore Colts, the Oakland Raiders and the Houston Oilers.
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Photos: Athletes and CTE
Former Minnesota Vikings linebacker Fred McNeill died in November 2015 due to complications from ALS. However, an autopsy confirmed that he suffered from CTE. What makes McNeill's case even more remarkable, though, is that he was potentially the first to be diagnosed while alive. Doctors used an experimental new technology to examine his brain.
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Photos: Athletes and CTE
Oakland Raiders quarterback Ken Stabler, a former NFL MVP who died in July 2015, suffered from CTE, researchers at Boston University said.
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Photos: Athletes and CTE
Kansas City Chiefs linebacker Jovan Belcher shot and killed his girlfriend before killing himself in December 2012. Pathology reports show he probably had CTE.
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Photos: Athletes and CTE
Hall of Fame offensive lineman Mike Webster was the first former NFL player to be diagnosed with CTE. After his retirement, Webster suffered from amnesia, dementia, depression, and bone and muscle pain.
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Photos: Athletes and CTE
The death of 36-year-old Pittsburgh Steelers offensive lineman Justin Strzelczyk put the link between football and CTE in the national spotlight. Strzelczyk was killed in a 2004 car crash crash after a 40-mile high-speed chase with police in New York.
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Photos: Athletes and CTE
Evidence of CTE was found in the brain of football player Lew Carpenter after his death in 2010 at the age of 78.
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Photos: Athletes and CTE
Pro Football Hall of Famer Louis Creekmur, who played for the Detroit Lions from 1950 to 1959, suffered decades of cognitive decline before his death.
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Photos: Athletes and CTE
Linebacker John Grimsley of the Houston Oilers died of an accidental gunshot wound to the chest in 2008. Analysis of his brain tissue confirmed damage to the neurofibrillary tangles that had begun to affect his behavior and memory.
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Photos: Athletes and CTE
Chris Henry played five seasons for the Cincinnati Bengals before dying at the age of 26. He died after falling from the bed of a moving pickup during a fight with his fiancée. His young age prompted concern over how quickly athletes start to suffer from CTE.
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Photos: Athletes and CTE
Offensive lineman Terry Long of the Pittsburgh Steelers committed suicide by drinking antifreeze. Although the antifreeze caused swelling of the brain, football-related brain injuries were a contributing factor to his death.
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Photos: Athletes and CTE
Pro Football Hall of Famer John Mackey suffered from dementia for years before dying at the age of 69.
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Photos: Athletes and CTE
Ollie Matson, who played 14 NFL seasons starting in the 1950s, suffered from dementia until his death in 2011.
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Photos: Athletes and CTE
Andre Waters spent most of his 12 seasons with the Philadelphia Eagles before his suicide at age 44.
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Photos: Athletes and CTE
Tom McHale of the Tampa Bay Buccaneers, right, died in 2008 of an apparent drug overdose at the age of 45.
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Photos: Athletes and CTE
Junior Seau took his own life in 2012 at the age of 43. The question of CTE came up immediately after his death; scientists at the National Institutes of Health confirmed the diagnosis in January 2013.
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Photos: Athletes and CTE
Pro wrestler Chris Benoit was found dead at his suburban Atlanta home along with his wife, Nancy, and son in an apparent murder-suicide. Testing found that the damage to his brain was similar to that of an elderly Alzheimer's patient.
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Photos: Athletes and CTE
Reggie Fleming, who played for six NHL teams, was the first hockey player to be diagnosed with CTE.
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Photos: Athletes and CTE
Hockey player Bob Probert was found to have CTE after dying of heart failure at the age of 45.
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Photos: Athletes and CTE
Ryan Freel became the first Major League Baseball player to be diagnosed with CTE nearly a year after he committed suicide at age 36.
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