Correlation Does Not Equal Causation.
Sometimes things are related. But it does not mean one is caused by the other. Science moves slowly and cautiously and now a study has been published taking the important step saying repetitive head impacts in fact “cause” CTE.
A research paper, published in Frontiers of Neurology titled Applying the Bradford Hill Criteria for Causation to Repetitive Head Impacts and Chronic Traumatic Encephalopathy, makes this important assertion.
In the paper the authors applied the Bradford Hill criteria to the medical literature dealing with CTE and repetitive head impacts. These criteria “provide a framework to determine if one can justifiably move from an observed association to a verdict of causation“.
In applying this criteria the authors “found convincing evidence of a causal relationship between RHI and CTE, as well as an absence of evidence-based alternative explanations“.
The authors published the following conclusions which have widespread implications spanning areas such as public health policy, sports regulation and even litigation.
The evidence on the link between RHI and CTE is imperfect, and like all similar research, it will remain imperfect in perpetuity. After reviewing the medical literature on RHI and CTE through the Bradford Hill criteria, we have the highest confidence in the conclusion that RHI causes CTE. We encourage the medical, scientific and public health communities to now act under the premise of a causal relationship and take immediate action to prevent CTE, minimize risk, and develop therapeutics to slow or stop disease progression.
To accomplish this, we must make greater investments in research to better understand the mechanism of CTE and develop biomarkers to diagnose CTE in vivo and measure the effect of interventions. We need to accelerate research to advance our limited understanding of the role of genetic and non-genetic risk factors and risk modifiers in CTE outcomes, anatomic location, symptomatology, progression, and severity.
Additional research will inform prevention and therapeutic strategies for the hundreds of millions of individuals worldwide already exposed to RHI and at risk of developing CTE. However, while we call for more research, we also believe that the strength of the current evidence compels us to move past a scientific discussion focused solely on filling gaps in the evidence to focus on immediately implementing aggressive CTE mitigation programs, especially for children.
We support measures to minimize and eliminate RHI as the best action for preventing CTE. We encourage awareness efforts so parents, athletes, and policymakers can better understand the risks associated with RHI, change how games are played to reduce or eliminate RHI – especially for children – and make more informed decisions regarding participation in contact sports.
Finally, we encourage the medical, scientific, and public health community to reflect on the risks of RHI to children, a vulnerable population that cannot provide informed consent to participate in activities that may cause a preventable neurodegenerative disease. We can, and should, do what is possible to prevent children from developing CTE before they can possibly understand how CTE might impact their future.