Mike Webster was the first.
The Pro Football Hall of Fame center for the Pittsburgh Steelers died in 2002. During an autopsy on Webster’s body, forensic pathologist Bennet Omalu identified a new kind of brain injury he coined chronic traumatic encephalopathy, or CTE.
In the years since, Omalu’s work, and the NFL’s attempts to discount it, have been the subject of a major film. That work has also led to more research and study, the results of which have shaken the world of football. A landmark 2017 study by Boston University researchers found that the brains of 110 of 111 deceased NFL players they examined showed signs of CTE.
The revelations of the past several years have brought the NFL into awareness of the problem its sport faces. Several players have retired early, fearful that the brutal sport will leave them with the irreversible brain damage CTE causes.
Others, like former Kansas City Chiefs running back Larry Johnson, wonder if their mood swings, self-destructive behavior, and memory loss are because of CTE. Johnson, who retired in 2011, told The Washington Post in December that he cannot remember two full seasons of his NFL career and that he regularly battles impulses to harm himself.
What is CTE, or chronic traumatic encephalopathy?
Chronic traumatic encephalopathy is a neurodegenerative disease. Over time, it causes nerve cells in the brain and parts of the nervous system to deteriorate and die. “CTE is unique but not unlike other neurodegenerative diseases such as Parkinson’s disease and Alzheimer’s disease,” says Jesse Mez, MD, an assistant professor of neurology at Boston University’s CTE Center.
What causes CTE?
“In our case studies, we have not seen cases of CTE without exposure to repetitive head impacts,” says Mez.
One type of brain trauma caused by head impacts is concussion, a mild form of brain injury that can cause confusion, blurred vision, nausea, headaches, and other symptoms that usually go away within a short amount of time. Less severe hits to the head also may contribute to CTE.
People who play contact sports like football and boxing appear to be more likely to get CTE because blows to the head happen often in such sports. And the such injuries are becoming more common. In recent years, the number of traumatic brain injuries in sports and other recreational activities has more than doubled among children, according to the CDC.
Two things appear to raise players’ chances of having CTE:
The age they start playing contact sports. A recent study found that kids who play tackle football before age 12 had more severe CTE-related symptoms later in life than kids who start to play at 12 or older. Another recent study showed that a single season of football caused brain changes among 25 players ages 8 to 13, even though none of them had had a concussion.
How long they play contact sports. The longer an athlete’s career, the more likely he is to get CTE and the more severe that CTE will be.
However, much remains unknown, says Mez. Scientists can’t say how many hits it takes to cause CTE or how long someone must play before the risk becomes serious. In fact, different people respond differently to head trauma, he says.
“In two people who had the same amount of exposure to football, one may develop the disease and another may not, or one may have severe disease and one may have mild disease,” he says. “That suggests that there are other risk factors, like genetics.”
What are the symptoms of CTE?
The symptoms of CTE, which are similar to other neurodegenerative diseases, include:
- Loss of memory
- Confusion and flawed judgment
- Changes in mood, personality, and behavior, which can include depression, anxiety, suicidal thoughts and actions, and aggression
- Dementia, in the disease’s later stages
Symptoms of CTE often begin long after the person with the disease last had a blow to the head.
How is CTE diagnosed?
Right now, CTE can only be diagnosed by examining the brain after death. But, says Mez, “we’re working really hard to come up with criteria to diagnose it in life.”
He says doctors likely will look at several things to make a diagnosis:
- The presence of a biomarker, or physical substance in the body, that indicates CTE. No such biomarker has been identified.
- A clinical history of symptoms
- Repeated hits to the head
In November, Omalu reported some hopeful news. An experimental brain scan he came up with positively identified signs of CTE in former NFL player Fred McNeill in 2012. When he died in 2015, an autopsy later confirmed those test results. But this was only a single case, Mez says. Much more research will be needed to confirm that the test will be useful.
Is CTE reversible or curable? And how is it treated?
It's not reversible or curable. Mez says there can be no therapies to treat CTE until it can be diagnosed in living patients. However, some of the symptoms can be treated. For example, behavioral therapies can help treat mood changes.
Mez says that because CTE shares many traits of Alzheimer’s and other neurodegenerative diseases, it may respond to treatments for such conditions. But, he cautions, “we haven’t had a lot of success with treating Alzheimer’s, and we know a whole lot more about that disease. … I think we’re some time away from therapies.”
What sports are most likely to be affected? And how many cases are confirmed, and due to what sport?
Football, hockey, boxing, soccer, and rugby are among the contact sports that make players most likely to have CTE. Members of the military also have a higher chance of having it. But, says Mez, statistics are scarce: “We really don’t have a sense of the incidence or prevalence of this disease at all.”
That said, CTE may be quite common among NFL players. Researchers at Boston University’s CTE Center studied the brains of 111 former NFL players. In a July 2017 study published in JAMA, they revealed that 110 -- or 99% -- of those brains tested positive for CTE.
Mez, the lead author of the study, says he knows the study had shortcomings. For example, brains donated for research were more likely to come from families of players who had shown symptoms of CTE, rather than from a wider group of players. That limited the researchers' ability to tell how common the disease is among pro football players. But the study, which also found very high levels of CTE among former college football players, was alarming.
What is the NFL doing and saying about CTE?
The NFL, which had disputed the link between football and brain damage, supports efforts to protect its players from CTE and other injuries. The league recently contributed $40 million toward medical research, with a focus on neuroscience, says Allen Sills, MD, who was named the NFL’s first chief medical officer in March 2017. The neurologist and sports doctor formerly co-directed Vanderbilt University’s Concussion Center and served there as a professor of neurological surgery.
Agreeing that there's a need for more research into CTE, concussions, and related issues, Sills says, “the NFL has been a leader on safety and has made real strides to try to better protect its players and make our game safer.”
He outlines several steps the league supports, including:
- “Data-driven” rule changes to end dangerous game tactics and make injuries less likely
- New guidelines, medical support, and technology to identify, diagnose, and treat concussions and other injuries
- Mandatory health and safety education for players and training for medical personnel
New rules for protective equipment
Is there any way to prevent CTE?
One thing that makes CTE unlike other neurodegenerative diseases, says Mez, is its clear link to “environmental exposures.” In other words, the likely cause -- repeated blows to the head over time -- is both known and preventable. For Mez, that means rethinking how we play sports.
“There are plenty of ways to play team sports and get cardiovascular exercise short of hitting your head repeatedly,” he says. “Should youths be playing contact sports? Should adults be playing contact sports? Those are really important societal questions that we should be asking.”
Some researchers say that future drugs may halt the CTE-related buildup of tau proteins in the brain caused by repeated blows to the head. While drugs that target such proteins are being developed, none have been effective.
What is the future of CTE research? What’s coming next?
In addition to coming up with diagnostic tests for people living with CTE and therapies to treat the disease, Mez says it’s crucial to identify who is most likely to get CTE. Genetics likely plays a role in that.
Some research now focuses on whether an Alzheimer’s-related gene, APOE-4, impacts CTE as well. Scientists also are looking at how certain genes may make a person more liable to get a buildup of tau proteins in the brain, an indicator of CTE and other neurodegenerative disorders.
What’s been the impact of CTE? Fewer kids playing football? High-profile players retiring earlier?
Since 2009, the number of boys ages 6 to 12 who play tackle football has dropped by 20%. But more recently, participation has rebounded slightly. In 2015, it rose by 1.2%. An estimated 2.2 million now children play tackle football.
Some NFL players have spoken out about CTE and related issues, like concussions. In December 2017, Washington Redskins quarterback Kirk Cousins told Sports Illustrated that he would take a test for CTE if one is created. Cousins and Seattle Seahawks defensive end Michael Bennett told SI that they would retire if they tested positive. In the same roundtable discussion, Artie Burns, a Pittsburgh Steelers cornerback, said he thinks he has CTE already: “I definitely know I have it … I don’t need a test. … Humans are not made to run into each other.”
Some NFL players, such as John Urschel, A. J. Tarpley, and Chris Borland, have retired early over concerns about brain injuries.