Home » Head Trauma Strongly Linked To Chronic Traumatic Encephalopathy But Precise Relationship Not Yet Known

Head Trauma Strongly Linked To Chronic Traumatic Encephalopathy But Precise Relationship Not Yet Known

Other risk factors for CTE, incidence rate not yet known; connection has been "greatly overstated" says Cantu


Prevention and treatment

The simplest way to decrease the risk of CTE, whatever it is, say a growing number of experts, is to:

  • limit exposure to trauma by reducing helmet-to-helmet contact in football through the teaching of proper tackling technique;
  • limit exposure to trauma through rule changes and better rules enforcement (such as by penalizing intentional hits to the head, as is happening in football and, to a lesser extent, in ice hockey);
  • limit exposure to impacts that may result in concussion or mTBI from subconcussive blows by reducing the number and length of full-contact practices.  Given the potentially large number of head impacts a football athlete may experience over the course of the season and their career, some experts have suggested implementing head impact monitoring and impact limitation strategies similar to pitch counts in baseball.  
    • Limits on full-contact practices have begun to implemented at every level of football, from the National Football League to college football (Ivy League and Pac-12) to the high school level (a growing number of state athletic associations have begun limiting full-contact practices, both in the pre-season and regular season, especially since the National Federation of State High School Associations recommended such limits in November 2014), and down to the youth level (Pop Warner). All are intended to limit the amount of total brain trauma football players sustain as a result of repetitive sub-concussive hits 
    • A 2013 study [16] found that limiting or eliminating contact practices in high school football would result in an 18% to 40% reduction in head impacts respectively over the course of a football season (regular season and playoffs), but says that, until the risk factors for CTE are better defined, and research shows that reducing the time spent learning to tackle in practice will not lead to increased risk of concussions in games, policymakers should proceed with caution in imposing such limits. Lead author, Steven Broglio, PhD, ATC, of Michigan NeuroSport and Director of the NeuroSport Research Laboratory at the University of Michigan, while recognizing that "contact sport athletes appear to be at a greater risk for developing CTE,"  was careful to note the absence of studies "indicating the relationship between head impacts, concussions, and other factors (eg. genetic profile) that may trigger the disease pathway." Until the risk factors for developing CTE are better defined, Broglio says, the effect of reducing impacts by 18% to 40% in the risk for CTE is "unknown" and strategies designed to reduce those risks will necessarily remain "an educated guess, at best. ... Ultimately, a comprehensive approach that includes, but is not necessarily limited to, modifications of head impact exposure, equipment modifications, rule changes and enforcement, and changes in game culture may all be needed to reduce injury risk," Broglio concludes.    
  • using more conservative return-to-play guidelines: Because the absence of observable symptoms may not be a reliable guidepost (some indications of impaired brain function are not detectable except with very sophisticated brain imaging equipment), some experts propose return to play guidelines requiring at least 4 to 6 weeks before a return to contact sports to facilitate more complete recovery and to protect against reinjury, as research shows that a second concussion occurs much more frequently in the immediate period after concussion. MomsTEAM's expert sports neuropsychologist, for instance, recommends in her 2012 book, Ahead of the Game: The Parents' Guide to Sports Concussions, that young athletes with diagnosed concussion not return to play for at least three weeks after injury.  Animal studies suggest there is an expansion of brain injury and functional recovery is slowed if the animal is subjected to overactivity within the first week (supporting the concept of cognitive rest recommended for children and adolescents);
  • proper care and management of mild TBI (cognitive and physical rest in the period immediately after concussive injury, gradual return to a full academic day, e.g. "return to learn") and following a six-step process of gradually increased exercise (without concussion symptoms returning) before return to play; and
  • player and coach education.

No consensus on causation

Rejecting the blanket conclusion that there is a definitive causal and effect connection between repetitive head trauma and CTE, the most recent international consensus statement on concussion in sport ("Zurich statement") [13] cautions that a relationship has "not yet been demonstrated between CTE and concussions or exposure to contact sports."  

It notes that "there are no published epidemiological, cohort or prospective studies relating to modern CTE. Owing to the nature of the case reports and pathological case series that have been published [including the McKee studies], it is not possible to determine the causality or risk factors with any certainty."

"As such, the speculation that repeated concussion or subconcussive impacts cause CTE remains unproven," the Zurich statement continues. "The extent to which age-related changes, psychiatric or mental health illnesss, alcohol/drug use or co-existing medical or dementing illnesses contributed to this process is largely unaccounted for in the published literature. [As a result], the interpretation of causation in the modern CTE case studies should proceed cautiously."   

Remarkably, the Zurich statement discussion of CTE concludes with a direct shot at the media in which it recognizes the importance of addressing the "fears of parents/athletes from media pressure related to the possibility of CTE."  Such a view is echoed by Randolph in the 2013 NFL retiree study[26] which laments that "the media attention to this issue continues to far outweigh any meaningful results from sound experimental science," and in four other recent literature reviews.[39-42]

"Doth protest too much, methinks"[29]

There was, not surprisingly, immediate pushback upon the Zurich statement's release in March 2013 from the research group at CSTE, the group most associated with the argument - repeated by many in the media - that such a causal connection has already been proven.

Said one of the Zurich statement co-authors, Dr. Robert Cantu, MomsTEAM concussion expert emeritus and CSTE director, in an interview with NewJersey.com. [15] "When I saw that [it said] we need more data in terms of CTE, I wrote to the other authors, in essence, 'What the hell do you mean that we need more data?' The whole breadth of the document is large, and 99 percent of it it I strongly support. But that part of it, I don't support at all. Frankly, it stunned me."

Dr. Cantu's colleague, Dr. Ann McKee, likewise expressed befuddlement at the Zurich statement's treatment of CTE, telling NewJersey.com, "This is a time that calls for immediate action to reduce the amount of head trauma experienced by athletes in all sports to prevent CTE."  She asserted that it would be "irresponsible to justify inaction by requesting a level of scientific proof that will take decades to acquire,"  expressing the fear that, to suggest that CTE "may not be part of the impact exposure, but rather due to other yet unidentified factors," could give tacit permission to those who play collision sports to proceed as if there is no urgent problem when concussions arise.

It wasn't intended to have such an implication, Dr. Rosemarie Scolaro Moser, MomsTEAM.com's sports concussion neuropsychologist, told NewJersey.com.  Instead, she cautioned that it would be jumping to conclusions to say, 'If you play football, you're probably going to get CTE.' Which is not the case. So what differentiates those with CTE from those who don't have it? That's what we need to know."

[Update: it is important to note that the Zurich statement was issued after a conference held more than three years ago, so that, in light of the body of research in the last three years, its statements on CTE may now be outdated.  What the 5th International Conference - rumored for Berlin in October 2016 - will decide is anybody's guess.  Stay tuned!]