Risk in rugby: a review

Professor Mark Bailey, Managing Director of Dukes Education, and Professor of Late Medieval History at the University of East Anglia, discusses the potential link between contact sports, such as rugby, and neurodegenerative diseases

Aspate of recent media stories — such as that detailing the distressing descent into dementia of 2003 England Rugby World Cup winner Steve Thompson — has drawn attention to the likely link between contact sports and neurodegenerative diseases. For parents of pupils at schools where contact sports are compulsory, and who are already concerned about heightened levels of injuries, these stories serve to pour fuel on the fires of their anxiety about contact sport. But can we peer through the (understandable) media interest and the clouds of anxiety to assess the actual hazards and the risks clearly and coolly?

There is no doubt that governing authorities in sport are taking the matter seriously. Four years ago I participated voluntarily in a UCL-led study to establish the incidence of neurodegenerative diseases among a sample of 250 former England and Oxbridge rugby players. Very recently, the findings of a very similar research project, promoted by the Scottish Rugby Union and undertaken by the University of Glasgow, was published and attracted glaring media attention.

The 2022 Scottish study provides an opportunity to explore some of the wider issues. It drew upon 32 years' worth of public health data to track the health of 412 Scottish men's international rugby union players with 1,236 members of the public. It found no differences between the two samples in respect of deaths from the most common causes of male deaths, such as heart and respiratory diseases and cancer. The elite rugby players even lived longer.

However, the study found that the chance of being diagnosed with a neurodegenerative disease was 11.5 per cent for the rugby sample yet 5.5 per cent for the general sample. Specifically, the incidence of dementia for rugby players was twice as high, of Parkinson's disease three times, and of motor neurone disease (MND) 15 times as high as the general male population. The position played on the rugby field — forwards or backs — made no difference to the level of neurodegenerative incidence.

It is worth pausing for a moment to unpick these findings, suitably detached from anxieties and the desire of journalists to generate a headline and also to remind ourselves of the distinction between incidence, hazard and risk; and between correlation and causation. The first point to make is that the research has established unequivocally a higher incidence of neurodegenerative disease among elite rugby players. From this research, we can reliably and reasonably conclude that neurodegenerative disease is a hazard — a source of harm — for elite rugby players.

The second point is that, until recently, this hazard was partially hidden or unknown. Previous generations of elite rugby players and coaches were not aware of it. In contrast, everyone understands the risks that scaffolders face because they are axiomatic and manifest. Now the hazard is known, rugby authorities have to promulgate this finding widely, so that players can understand the increased incidence of harm they face. Players can then make their choices, no less than scaffolders.

But what else can we deduce from this research? In the press stories that followed, one of the leadresearchers called on the rugby authorities to drastically reduce the number of games and especially the frequency of physical contact in training. He was quoted as saying “the modern game from 1995 onwards has seen head injury exposure go up and up and up, as far as I’m concerned.” Here the researcher jumps from the bounds of the carefully conducted methodology and findings into personal speculation, without obviously flagging the leap.

In reality, the research did not produce definitive proof that contact with the head is the single major risk in the rugby hazard of neurodegenerative disease. And it did not prove that head injury exposure has increased exponentially since the introduction of professionalism in 1995. Both of these statements might be true, but there is no proof in the Scottish study. The researcher was offering subjective deductions about causation, which are unquestionably comprehensible and logical, but nothing more. Perhaps the researcher did make these distinctions before opining, but the caveats and context were not reported.

The response to the report from the Director of Research into Motor Neurone Disease at a leading Scottish charity was much more measured. Dr Jane Haley welcomed the research, but pointed out that the sample sizes were very small. She also observed that “the reasons for these apparent increases are not yet known, and need to be explored further”. Her caution is fittingly cautious and proportionate to the findings of the study, although presumably she would be willing to receive funding to conduct that further research.

What Haley was saying is that the risks surrounding neurodegenerative disease within elite rugby remain uncertain. In this context, we are defining risk as behaviour, actions, inactions, or events that increase the chances of triggering the hazard, and/ or increasing its severity. Contact to the head seems the most likely risk, which is why rugby authorities around the world are treating any head injury with much greater seriousness and caution, but it remains unproven. One alternative theory suggests that certain genetic profiles, when conditioned by the highest levels of physical activity and stress associated with elite sport, are the main risk factor.

Even if head injuries are eventually proven to be the main risk, we need to understand what type of head injury, and whether single trauma or repetitive strain; and we need to understand when they most occur, i.e. what facets of a rugby match, and whether player fatigue is a factor. Once these are known, the nature of the game can be changed accordingly to reduce risk and other targeted preventative measures taken.

Hence three simple pleas. The first is for an explicit separation at all times between a hazard, its incidence, and the risks that trigger it. Second, for researchers and journalists to be clear when they jump from the narrow findings of their research to personal speculation about causes. Third, widespread awareness of the hazards of contact sport, so the individual can make informed choices about participation. n