In a decision that will have repercussions for contact sports, the US National Institutes of Health have formally recognized a causal relationship between repetitive head trauma and the neurodegenerative disease chronic traumatic encephalopathy (CTE).
The NIH is the nation’s largest scientific research organization, and the move to update their official guidance on CTE has been regarded as a turning point in the argument over the dangers of collision sports by advocacy groups. In the judgment of the NIH, the causal connection between recurrent traumatic brain damage and CTE is apparent and unambiguous.
This position contradicts that of the Concussion in Sport Group, which is backed by Fifa, World Rugby, and the International Olympic Committee, among others. The CISG consensus documents on concussion have continuously minimized the relationship between CTE and sport-related brain injury.
The most current one, dated 2017, notes that “to date, a cause-and-effect relationship between CTE and concussions or exposure to contact sports has not been demonstrated,” a position referenced by several sports federations in their defense against legal challenges and calls for reform.
In response to a petition signed by 41 prominent scientists, physicians, and epidemiologists, the National Institute of Neurological Disorders and Stroke revised its guidelines (Ninds). The letter noted a recent review of CTE data published in July in the journal Frontiers in Neurology, which demonstrated a causal link between CTE and the types of recurrent brain damage encountered by abuse victims, soldiers, and athletes in particular.
Since the disease was first identified in the 1950s, there has been evidence that this is the case. In 2014, the director of Ninds stated that the causative relationship was “quite evident,” but their official guidelines did not reflect this until recently.
The shift aligns the NIH with the 2019 advice of the US Centers for Disease Control and Prevention, which stated: “The majority of data suggests that CTE is partially caused by repeated traumatic brain injuries.” It indicates that two of the world’s foremost independent medical research organizations concur on the etiology of CTE.
It remains to be seen whether this will be reflected in the CISG’s next concussion consensus. The committee is hosting a conference in Amsterdam on Thursday and Friday to prepare the most recent version of the consensus, which will be published in the first quarter of the following year.
Dr. Paul McCrory, the chair and principal author of the CISG resigned earlier this year amid allegations of repeated instances of plagiarism in his work. As a result, the CISG is already the subject of heightened scrutiny. McCrory was cited on Retraction Watch at the time apologizing and stating that his failure to attribute was neither deliberate nor intentional.
A spokeswoman for the nonprofit organization Concussion Legacy Foundation stated, “Now that causation has been demonstrated, the world has a tremendous chance to avoid future occurrences of CTE.” “The sole known cause of CTE is environmental exposure, and in the majority of instances, a choice — the decision to participate in contact sports.”
“Our objective is to modify all youth sports so that they do not include preventable recurrent head hits before age 14 – no heading in soccer, no tackling in [American] football and rugby. This measure, together with sensible limitations to repetitive head hits in sports for those over 14 (such as no hitting in football/rugby practice and stringent limits on headers in practice), should avoid the vast majority of future CTE cases.
