The Challenge of Head Injuries & Concussions, in Contact Sports, to Modern-Day Society

Recent studies have greatly increased public awareness of specific sports injuries, particularly traumatic brain injuries (TBIs). To be more specific, TBIs are more than just consuccions. Overall, accidents are the fourth-leading cause of death in the U.S., with over 22% of those (~%50,000) related to TBIs (1). While all-cause TBIs have increased in recent years, particular attention has been directed toward sports-related TBIs, and in particular, brain risk in professional athletes in the American National Football League (NFL). In 2016, the NFL settled a $1 billion lawsuit by former players with maladies related to TBIs. This settlement allowed the NFL to avoid admitting fault, or disclose their level of knowledge of TBIs, the basis for thousands of lawsuits by individual players. The settlement covers 20,000 former players, over the next 65 years, for neurodegenerative diseases, including dementia, advanced Alzheimer’s, Parkinson’s, and Lou Gehrig’s (amyotrophic lateral sclerosis) diseases (2).

In many cases, including football, the genesis of TBIs is caused by head collisions in which the brain, free-floating in cerebrospinal fluid, collides with the source of primary impact, generally at the front of the skull (“coup”, Fig. 1, left) (3). If the impact is strong enough, collision at the front skull can create a backward force and brain impact at the rear of the skull (“contrecoup”, Fig. 1, right) (3). While helmets are well designed to prevent skull fracture, they offer little or no protection from brain-skull collisions (3).

Figure 1. Collision-induced brain injuries. Left, site of primary contact, generally at the front of the brain (“coup”). Right, secondary impact, at the rear of the brain (“countercoup”). (by Mosby, Inc., an affiliate of Elsevier, 2007, 2011).
In the NFL settlement, a separate fund ($675 million) was specifically set aside for those suffering from chronic traumatic encephalopathy (CTE), a TBI-induced, neurodegenerative disease caused by repeated TBIs (both symptomatic and asymptomatic), up to $4 million per players. While previously reported, in 1973, in boxers (4), CTE had not been reported in football players, prior to 2005. In that year, CTE was found upon autopsy of a deceased NFL player, Mike Webster (“Iron Mike”). Webster, a Hall of Fame inductee and 9-time All-Star lineman for the Pittsburgh Steelers, is considered to be one of the best centers of all time (5). Webster sustained multiple concussions throughout his playing career. After his retirement in 1991, it was medically undisputed that he was permanently mentally disabled, suffering from amnesia, dementia, and depression, largely living out of his truck in Pittsburgh (even while declining friends’ offers to pay his rent) (6). His latter years, death, autopsy by the Nigerian-born pathologist, Bennet Omalu, and continued litigation again the NFL, were portrayed in the 2016 film, Concussion, starring Will Smith as Omalu (7). In 2005, Omalu published Webster’s autopsy findings, "Chronic Traumatic Encephalopathy in a National Football League Player" (8). However, that publication remained largely ignored, even with demands of its retraction (9), by the NFL’s Mild Traumatic Head Injury Committee.  This counterattack by the NFL, continued until 2013, and the 2016 settlement described above
Dr. Bennet Omalu

In 2002, Omalu cofounded the Brain Injury Research Institute (Wheeling, WV), dedicated to the study of concussions, and primarily, CTE.   Unfortunately, CTE can yet only be identified by post-mortem brain autopsy. Similarly, concussions (or even repetitive head blows without concussion) increases the risk of all types of neurodegenerative diseases. Specifically, one analysis of retired NFL players’ death certificates revealed a three-fold elevated rate of dying from Alzheimer’s disease and ALS, compared to incidence in the overall population(10).  However, while impossible to distinguish from other progressive neuropathologies (in living persons), CTE is a distinct malady, with four progressive stages that ultimately lead to loss of motor function and memory loss, that mimic advanced ALS, including brain accumulation of the protein tau, but not beta-ameloid, with the latter being characteristic of Alzheimer’s disease (11) (Fig. 2).  

In addition to full-fledged, symptomatic concussions, however, the potential pathology of (asymptomatic) mild TBIs (mTBIs), is only now coming to light. MTBIs are now believed to similarly associate with neurodenerative disorders, including CTE (12). In the largest modern autopsy series to date, including 82 amateur athletes exposed to repetitive mTBIs (“subconncussive” head blows), identified evidence of CTE in 68 (80%) (11). Another MRI study showed that 76% of professional boxers had abnormalities in brain areas involved in memory and complex visual processing, injuries to nerve cell axons, and breakdown of the protective brain blood barrier.(13) Such post-concussive injuries depend largely on the number of bouts and number of rounds. However, the sport associated with the greatest number of concussions (even more than football and hockey players and boxers) is mixed martial arts, with almost one-third of bouts ending in knockout or technical knockout (14). Consequently, the American Medical Association has proposed a ban on this sport in children (14).

While recent attention has primarily focused on professional football players (who number less than 2000), perhaps even more disturbing, are revelations of TBIs in youth sports, primarily football (with over 3 million participants in 2014). Football-related TBIs

source: Boston University Center for the Study of Traumatic Encephalopathy
Figure 2. Normal (left) vs. CTE (right) post-mortem brain tissue (source: Boston University Center for the Study of Traumatic Encephalopathy).

account for >64% of the 400,000 sports-related injuries (thus, ~ 290,000) seen annually in emergency departments (15).  In particular, the developing brains in children and adolescents are more susceptible to brain injuries, compared to adults, with the brain not reaching its full development until the ages of 18-25 (16). Although directly fatal TBIs remain rare, recent studies are now investigating the cumulative effect of repeated mild TBIs (mTBIs), in high school and college football players. Thus, repetitive sub-concussive hits to the head can cause as much damage as concussion-causing hits, with one theory hypothesizes that CTE may coexist with other neurodegenerative diseases, including Alzheimer’s disease (17).

Another head collision study, using specialized helmet telemetry sensors in 95 high school football players, found an average number of 652 head impacts, per player, over a 14-week season. However, the collision numbers varied widely per position, with offensive and defense linemen having over 1000 (18). Another report of changes in the brains of high school football players who had suffered concussions, with the brains of football players who were concussion-free, revealed brain tissue damage in both (19). Further support for mild TBIs (mTBIs) was the finding of dose-response relationship between the number of head impacts and later-life cognitive impairment (20) According to the Brain Injury Research Institute, in any given season, 20 percent of high school players sustain brain injuries. Additionally, over 40.5 percent of high school athletes who have suffered concussions return to action prematurely (for many, the following day), which can potentially lead to death from Second Impact Syndrome (SIS). SIS is a condition in which, following previously inadequate healing from trauma, the brain swells, shutting down the brain stem, and resulting in respiratory failure, and death, in 50% of all cases (15). Thus, a disturbing consequence is that brain injuries could be occurring, resulting in cumulative damage, without knowledge by trainers or even players.

A fair question to be asked is: how, or will, these findings affect our societal attitude toward sports, particularly those involving heavy contact? Despite declining viewership from 2015 – 2017, the most recently completed television (all networks) NFL contract was $27 billion, over the nine-year period of 2014-2022, or an average of $3 billion per year (21). Combined with other revenue streams, the NFL took in an estimated $13.3 billion in 2016; this yearly amount is projected to exceed $25 billion in 2024. Of the 2016 revenues, $6.4 billion (48%) will be shared with the leagues 1800 players, about $35.5 million (21). Thus, in terms of total profits, the league has never been stronger.

Despite this prosperity, however, is some negative sentiment in players at the college and professional levels. Perhaps most disturbing is a cumulative finding that of 101 retired NFL players’ brain autopsies, to date, 80 have been found with CTE (21). Another significant problem for the NFL was the retirement by 19 players under the age of 30, prior to the 2016 season, forgoing any future accumulation of wealth (22). Further damaging the NFL’s public image was a New York Times story hinting that the league borrowed a defense strategy from the tobacco industry, with its medical committee publishing 13 articles downplaying the dangers of concussion (23). The NFL considered, but did not purse, litigation against the Times, for that piece (24). It also has been well argued that the NFL was aware of the head injury problem since at least the early 1990s (25). Another vexation might be continued litigation by 220 former NFL players who opted out of the $1 billion settlement in 2016 (26). In addition, a separate lawsuit has been initiated against the helmet manufacturer, Riddel, Inc. (Elyria, OH), similarly arguing intentional suppression of concussion knowledge (27).

Last August, Ann McKee, director of the Boston University Chronic Traumatic Encephalopathy Center, said that kids under 14 shouldn’t play football, noting that younger children’s heads are “a larger part of their body, and their necks are not as strong as adults’ necks (28). So kids may be at a greater risk of head and brain injuries than adults. Moreover, in 2011, the American Academy of Pediatrics and the Canadian Pediatric Society, published a joint statement vigorously opposing children’s participation in high-impact contact sports, purposely damaging their immature brains (29). However, in this instance, the example sport was boxing.

Similarly, Dr. Bennet Omalu, the discoverer of football-related CTE, wrote an op-ed in the New York Times, entitled “Don’t Let Kids Play Football.” In that piece, Omalu argues that even without full-fledged concussion, in the months following the football season, children’s brain damage can be detected at the cellular levels, with eventual permanent damage over several seasons. Omalu further likens youth football to smoking (unsafe at any level, but permissible after a legal age), even suggesting it akin to child endangerment (30).

In a retort to Omalu’s article, MacDonald et al. (2016) contend that inactivity in children is much worse than football, noting that CTE findings in NFL football may not be relevant to youth football, and that advancements in CTE knowledge now make the sport safer. These authors further assert that sports participation increases self-esteem and social skills, traits that extend into adulthood (31). Complicating matters further was a counter-retort to that comment, by Bullingham et al. (2017), asserting that contact sports, alone, are not a necessary remedy for sedentary lifestyles. These authors also note a British Sport Collision Injury Collective call to remove tackling from rugby, in May 2016, and that various CTE research initiatives have largely focused on primary prevention (avoiding injury altogether), rather that aftercare of existing TBIs (secondary prevention) (32).

The outcomes of these viewpoints, on youth football, remain unclear. Failure of a youth brain safety program entitled “Heads Up Football” (started in 2012) was just revealed recently (23), concurrent with boys’ participation in tackle football decreasing by 20 percent, from 2009 – 2014. However, participation again rose by 1.2%, in 2015. Moreover, U.S.A. Football, the governing body of the youth level of the sport, is trial-testing a new “modified tackle” format, having several rule changes, including each team having no more that six to nine players (instead of 11), a greatly shortened playing field, and kickoffs and punts eliminated. Widespread implementation of the format, however, is several years away, and the proposed changes have met skepticism by the medical community and safety advocacies (33).

In summary, only time will tell if these troubling discoveries significantly impact our favorite American pastime, football. To that end, it will be interesting if 2017 again brings retirement by players in the primes of their careers. Of even longer-term significance, however, will be the continuation, or reversal, of attrition at the youth and high-school levels. However, with the NFL finally acknowledging the existence of the problem, it is possible that improved equipment, adoption of non-head-involved tackling/blocking techniques, and recent awareness of sub-concussive, minor traumatic brain injuries will yet allow the sport to thrive and prosper.   


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