Simplistic commentary on rugby concussion unfair

Once again rugby union finds itself in the dock following publication of a Glasgow study reporting an increased risk of neurodegenerative disease, particularly motor neuron disease [MND], in retired Scottish amateur international rugby players. The study has attracted publicity in the popular press with headlines such as “Study finds rugby players 15 times more likely to be diagnosed with motor neuron disease”.

Like the many widely publicised studies on chronic traumatic encephalopathy (CTE) following sports-related concussions, the study has probably induced fear and anxiety among sports men and women. That some former rugby players have developed CTE is a fact. However, it is misleading to state that there are multiple autopsy reports confirming CTE in rugby players. Only four such reports are referenced in the Glasgow study.

At the heart of these widely publicised studies spanning all sports, is a blurring of the differences between relative and absolute risk for any individual. Risk and probability are not synonymous. Risk might refer to the presence of a dangerous substance with imminent danger to health or to the possibility of an adverse health outcome or to the probability of an adverse health outcome. How the public perceives risk is determined not by the statistical formulation in published studies but by how the media conveys risk.

It is accepted that brain trauma is one of the many risk factors contributing to later development of neurodegenerative disorders such as Alzheimer’s disease, Parkinson disease, MND and CTE. The relevance of, and correlation between, the severity and number of brain injuries with neurodegeneration remains the subject of much-needed research. Understanding the lifetime’s interplay between genes and the environment that culminates in a devastating fatal illness such as MND should not be reduced to simplistic commentary on a single sport. The discussion on CTE and neurodegeneration is relevant to Mixed Martial Arts, boxing, Gaelic football, hurling, soccer, cricket, and equestrian sports as head trauma occurs in each of these activities.

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What is certain is that for sportsmen and sportswomen there is a risk of tragic accidental death varying from high in motorbike racing to lower risk from equestrian sports including horse racing to Gaelic games. Adult participants in “risky sports” have decided that the benefits of participation outweigh the risk of death. For children, decisions about participation often rest with parents. To imply that parents who encourage their children to participate in contact sports, are somehow guilty of child neglect is but one of the many unfair statements that have contributed to a decline in childhood participation in all sports. Decreased exercise results in increased risk of obesity, diabetes, osteoporosis, and cardiovascular disease. Furthermore, we know that physical and mind exercise increases connectivity between the brain’s 100 billion neurons thus generating brain reserve to buffer against later life neurodegenerative disease.

[ Concussion not confined to rugby — and problem affects girls more than boys ]

How is the rugby player to weigh the risk of developing CTE or motor neuron disease? Does the risk apply only for elite international rugby players? We don’t know because the Glasgow study did not include a control group of non-elite rugby players. Is vigorous non-contact sports associated with an increased risk of developing motor neuron disease? For example, some athletes might share a specific genetic make-up that predisposes to better performance in high-level sport but with a parallel subsequent increased risk of developing motor neuron disease. Such a genetic background could interact with environmental factors, such as pesticide-exposure, increasing the athlete’s risk of developing motor neuron disease. However, we are in dark here as the Glasgow study did not include a control group of athletes from non-contact sport such as competitive running.

Not all “concussion” is concussion. Migraine, vestibular (inner ear) dysfunction, depression, and post-traumatic stress disorders are frequently mistaken for complex concussion or “delayed” concussion (whatever that is?). For example, approximately one third of athletes playing Gaelic football, hurling, rugby, or soccer referred for assessment of concussion to one of our neurology departments turned out not to have had concussion. Instead, they had similar overlapping symptoms due to migraine. Unfortunately, one of the triggers for migraine is head trauma. It is often very difficult to distinguish between a migraine attack triggered by head trauma from concussion symptoms. This is really important as migraine does not carry a risk of long-term dementia and sometimes the athlete is given the wrong advice.

[ Brian O'Connor: Rugby’s future under threat as more people ask is it worth the risk ]

It is accepted that more careful stringent research is needed. Prospective long-term studies to examine all aspects of brain structure and function, using the most modern genetic, radiologic diagnostic and concussion rehabilitation tools, will ultimately provide answers on the likelihood of developing long term consequences from sports-related concussions. Such research will take years to track sports men and women through life to death. Even then, the studies may present special challenges and yield incomplete results as they might necessitate randomisation into groups receiving the most up-to-date post-concussion care versus those randomised not to receive such care.

So, in the meantime all we can do is to ensure with the media’s help, that health research on sport continues to be fostered, that sports participation continues to increase, that safety measures are put in place (eg, below the waist tackle in rugby to avoid head clashes as both of us were taught in school) which reflect our current knowledge, and that neurology experts are involved in making a correct diagnosis of concussion. Specific targeted concussion treatments must be provided by brain experts. At the very least our sports men and women deserve the best advice available, advice that includes reassurance and which avoids the sensational headlines.

Tim Lynch is a Consultant Neurologist at the Mater Misericordiae University Hospital. Michael Farrell is a Consultant Neuropathologist Beaumont Hospital