The tragic toll from traumatic brain injury continues to climb among athletes who routinely hit their heads -- or use them as weapons -- during play on the field or fights on the rink.
The Boston University Center for the Study of Traumatic Encephalopathy, where researchers last spring diagnosed the late football star Dave Duerson as having chronic traumatic encephalopathy (CTE), now has 60 confirmed cases of athletes with CTE in its brain bank, according to neuropsychologist Robert A. Stern, PhD, co-director of the center.
Cases from the Gridiron
The first case of sports-related CTE was reported in Neurosurgery in 2005. The report enraged officials at the National Football League, who vehemently denied the possibility of a causal connection. By 2008, however, it had become clear that some football players indeed were experiencing sequelae of their frequent head trauma.
The Boston University research initiative was established at that time, soliciting tissue donations from deceased players. In addition to Stern, co-directors include Ann McKee, MD, Robert Cantu, MD, and Chris Nowinsky, a former football player and professional wrestler with a history of multiple concussions.
"When we first started our center three-plus years ago we expected to find CTE in a small number of athletes, and specifically in those who had a history of significant concussion," Stern told MedPage Today.
That turned out to be wrong. Not only have there been many more cases than anticipated, but many of the affected individuals had only subconcussive injuries – though lots of them.
"These are the types of hits that a lineman in football gets, where in every play of every game and every practice – some 1,000 to 1,500 times each season -- he hits his head against his opponents with a force of about 20 G, which is not a minimal force," Stern said.
The end results in susceptible individuals, according to autopsies done by his group, include widespread abnormalities similar to those seen in Alzheimer's disease, including neurofibrillary, glial, and astrocytic tangles and abnormalities in tau proteins.
The Rules Tighten
In response to the escalating concerns about brain injury, the National Football League has tried to crack down on dangerous play, instituting a program of enhanced enforcement for safety violations. This season, for instance, Detroit Lions player Ndamukong Suh received a two-game suspension after being observed stomping on another player's arm in a Thanksgiving Day game.
More recently, the Pittsburgh Steelers' James Harrison was suspended for one game in December as punishment for a helmet-to-helmet hit that left quarterback Colt McCoy of the Cleveland Browns with a concussion.
Even though the blow was witnessed by millions on television, the Browns' medical staff failed to realize he had suffered a head injury and cleared him to return to play a few minutes later. The Sport Concussion Assessment Tool -- mandatory in the NFL since 2009 -- was not administered to him until the next morning.
Stung by criticism of the oversight, the NFL responded this week with a new system in which trainers, stationed in the coaches' booth above the field, will watch specifically for potential concussions. They will then tell teams on the sidelines when they need to evaluate players with the assessment tool.
But a growing number of players are not satistifed with the NFL response and are determined to force the league to acknowledge their long-term health problems relating to concussions.
This week, four former players sued the NFL in U.S. District Court in Atlanta, according to an Associated Press report. In their lawsuit, Jamal Lewis, Dorsey Levens, Fulton Kuykendall, and Ryan Stewart allege that the league has been aware for decades of risks of head injury, and "has done everything in its power to hide the issue and mislead players associated with concussions." The players claim to experience problems such as headaches, memory loss, and sleep disruptions.
Hockey Under Scrutiny
The focus on head injury also now has expanded to violence on the hockey rink. The death of the National Hockey League player Derek Boogaard in May from an overdose of alcohol and pain killers, and the subsequent finding of extensive CTE – in a man only 28 years old – added to concerns about safety in contact sports.
Boogaard, known as Boogeyman, had been an "enforcer" for the NHL, meaning that he was a designated fighter who routinely collided with other players and engaged in fistfights on the ice to intimidate his opponents and delight the audience.
During the 2009-2010 season, he had been knocked down during a fight and struck his head on the ice, after which he complained of headaches. According to a story in the New York Times, he became withdrawn and sullen and was having memory losses while drinking heavily and taking numerous drugs such as oxycodone. He entered rehab, but left and became more reclusive, erratic, and returned to substance abuse.
He was found dead in his New York City apartment on May 13.
Unlike the NFL, the hockey league has shown no interest in banning fighting or otherwise changing the culture of the game, according to the Times article, despite the deaths of other scrappy players. These included Rick Rypien, who committed suicide at 27 after struggling with clinical depression during a career with the Vancouver Canucks marked by frequent fighting, and Wade Belak, who also had experienced periods of depression and died in uncertain circumstances at 35 after playing for a number of teams including the Toronto Maple Leafs.
The Alzheimer's Link
Research into CTE is still in its infancy, Stern said. But because of the similarity in pathologic findings between CTE and Alzheimer's disease, his group has been building on the substantial body of knowledge about Alzheimer's, using the latest technologies and techniques such as neuroimaging and basic science approaches.
"All the neurodegenerative diseases have complex neuropathogenetic pathways, involving genetics and epigenetics, environmental risk factors, and aging-related factors," Stern said. "Although the initiating event in CTE appears to be trauma, in all the neurodegenerative diseases early in the disease course there is some disturbance of neuronal integrity leading to a cascade of pathophysiologic events that ultimately results in neurodegeneration," he explained.
But not everyone with repetitive head trauma develops CTE, so Stern and his colleagues are now trying to tease apart other potential contributory factors, such as individual players' specific trauma history, age at first injury, total duration of trauma exposure, and the length of rest between injuries.
Stern also has recently been awarded a grant from the National Institutes of Health to develop biological markers that could be used to identify CTE earlier, rather than in postmortem neuropathologic exams. To do this, his group has enrolled 100 former NFL players who were linemen, linebackers, and defensive backs -- the positions with the greatest exposure to repetitive brain trauma -- and 50 noncontact sport athletes with no history of brain injury.
They are performing extensive clinical, neurologic, and neuropsychological examinations to look for factors common among those who develop the disease.
Stern and his colleagues also are collecting blood for DNA genotyping, doing lumbar punctures to analyze proteins such as tau, and conducting extensive brain scans including diffusion tensor imaging, as they puzzle out the steps in the lethal pathway to CTE.
Kids at Risk
It isn't just professional athletes who are at risk for these injuries. "We are appreciating more and more the particular potential vulnerability of, and long-term consequences to the young brain as a result of concussive and subconcussive brain trauma experienced through participating in certain youth sports," Michael Bergeron, PhD, of the University of South Dakota in Sioux Falls, told MedPage Today.
Participation in sports can provide numerous benefits to young people, as well as being fun. "However, the motivations of some adult stakeholders are sometimes in conflict with these objectives, and the professional model of development and high-impact styles of play for young players are increasingly encouraged, prevalent, and accepted," cautioned Bergeron, who is also the executive director of the National Youth Sports Health and Safety Institute.
"My hope is that there will be a change in the way children and adolescents train, compete, and safely return to play after an injury. By promoting healthy coaching, training, and competition overall and emphasizing fitness, skill acquisition, diversified athletic experiences -- and fun -- we can reduce overall injury risk, including head trauma," he said.