CTE: Media Continues To Be Ahead Of Science
McCrea and McCarthy were not alone in urging caution.
In a June 2013 meta-analysis of the scientific literature on CTE in the prestigious British Journal of Sports Medicine, Andrew Gardner, MD, of the Centre for Translational Neuroscience and Mental Health in Callaghan, New South Wales, Australia, and two highly respected colleagues, Grant Iverson of Harvard and Paul McCrory (the lead author of the last four international consensus statements on sport-related concussion, including the Zurich 2012 statement that prompted the expressions of outrage by Drs. McKee and Cantu), characterized the “strongly presented causal assumptions in the literature relating to concussive and subconcussive brain impact exposure” as “scientifically premature.”
Before such a conclusion could be reached, wrote Gardner and his colleagues, systematic research was needed to address five specific unanswered questions:
First, whether similar, or even identical, neuropathological findings are observed in other samples that share clinical characteristics with CTE, such as patients with drug or steroid abuse, alcohol abuse histories, chronic psychiatric problems, cardiovascular/cerebrovascular disease or other health conditions.
Second, the extent to which the reported underlying neuropathology contributes to the reported clinical features (e.g., cognitive deficits, psychiatric features).
Third, whether and to what extent genetics may contribute to the observed neuropathology.
Fourth, whether there are other possible mediator or moderator variables for the association between the neuropathology and the clinical features of the disease.
Finally, whether a methodology can be developed for identifying individuals who are at future risk or might currently have CTE.
“Psychiatric problems and cognitive impairment,” wrote Gardner and his colleagues, “usually have multifactorial, not unitary causation — this will require further attention in future studies.” He said that the important next step in the process of potentially answering some of the unresolved issues associated with CTE was to conduct large-scale, prospective, longitudinal, clinicopathological studies.
Both Drs. Cantu and McKee have also called for such studies, of course, and their group is leading a multi-center study led by the CTE Center’s clinical research director, Dr. Robert Stern, and backed by a $16 million grant from the National Institutes of Health, to gain a better understanding of CTE, its clinical symptoms, and the course of the disease.
But, in the meantime, it appears that the prevailing media narrative continues to be that those that play contact and collision sports in general, and football in particular, are at serious risk of developing a frightening, degenerative, irreversible disease, even though, as noted above and by Dr. McCarthy, “the study of head injuries is a lot more confusing and murky than once suspected — that some very good researchers are now suggesting CTE might not even be a unique disease.”
A note of caution
“The interpretation of causation in the modern CTE case studies should proceed cautiously,” urges a 2013 review of the scientific literature on CTE, whose authors included such pre-eminent concussion researchers as Willem H. Meeuwisse of the University of Alberta, and neurologist Jeffrey S. Kutcher, MD of the University of Michigan, a co-author of the 2013 American Academy of Neurology’s concussion guidelines, and co-author of a 2016 book, Back in the Game, in which he repeatedly and pointedly criticizes the media for “irresponsible” reporting on CTE.
“Studies examining a connection between sporting head injury and outcome are necessary,” writes Alan Carson of the University of Edinburgh in August 2017 in the British Journal of Medicine, “but it’s unhelpful when the results are rushed to mainstream media outlets before proper consideration to interpretation, limitations, and replication.” He argues that it is “unfair” to a public unfamiliar with the technical problems with these studies, such as reproducibility. “Researchers should exercise appropriate caution and responsibility in how they present, and more importantly disseminate, results.”
The authors of the Canadian study of CFL players agreed: “Our findings,” they said, “advocate caution in the clinical diagnosis of CTE in patients with histories of contact sports and neurocognitive decline, as other diagnoses of neurodegenerative diseases are also possible.”
It is important to note that these researchers are not saying that such a causal link won’t ever be established, and it is clear from the evidence so far that there is a link between concussions and repetitive head trauma and an increased risk of long-term neurocognitive problems.
Kutcher, for one, admits that, “Ultimately, scientific research might establish that participation in contact sports leads to a distinct neuropathological syndrome, and this neuropathology causes psychiatric, cognitive and physical problems.” Until then, such “cause and effect relationship remains to be shown scientifically.”
“Until the risk factors for developing CTE are better defined,” says Steven Broglio, PhD, AT, of Michigan NeuroSport and Director of the NeuroSport Research Laboratory at the University of Michigan, 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.