Ex-Rugby Players Face 15 Times Higher Risk of Motor Neuron Disease
A new study by researchers at the University of Glasgow has found that former Scottish international rugby union players have a higher risk of developing neurodegenerative diseases, including dementia, Parkinson’s disease and motor neuron disease.
The innovative study retrospectively examined players’ health records over several decades. In total, the study included data from 412 players and 1,236 non-players matched for age, sex and socioeconomic status.
While, ultimately, larger studies will be required to tease out all the details of the link between contact sport and neurodegenerative disease, this study’s lengthy follow-up period and design makes it a strong addition to the broad existing literature on the connection, say experts.
Contact sports and head injury
The research, published in the Journal of Neurology, Neurosurgery and Psychiatry, was co-authored by Prof. Willie Stewart, who last year published an analysis of the increased neurodegenerative disease risk faced by soccer players.
Recent research has shown a link between repeated exposure to head impacts, dubbed chronic traumatic encephalopathy (CTE), and neurological disease in cohorts of athletes from rugby union, soccer and American football.
Stewart’s team wanted to see if this risk held for retired rugby players over a lifetime. They looked at electronic health record data for their cohort – a trove of information that includes any hospital admissions, medicines prescribed and causes of death.
Over the period that the study examined, 29% of the rugby players died, as did 31% of the comparison group. Up until the age of 70, ex-rugby players had a lower rate of death than the comparison group from any cause. After 70, there was no difference with the comparison group. Ex-players also lived longer on average, dying at 79 compared to 76 for non-players.
Ex-players were not significantly more likely to die directly from cardiovascular disease, cancer, respiratory disease or neurodegenerative disease. But players were significantly more like to be diagnosed or hospitalized with a neurodegenerative disease; the risk was 2.29 and 4.59 times higher respectively. Players were also more likely to pass away with an incident neurodegenerative disease on their death certificate.
Doubled dementia risk
Stewart and his team next looked at risk for different subtypes of neurodegenerative disease. For all subtypes, ex-players had a significantly greater chance of diagnosis. Players faced roughly a doubled risk of dementia and a tripled risk of Parkinson’s disease. Their risk of contracting motor neuron disease was a massive 15 times higher.
Stewart’s team noted no differences between players’ position – forwards and backs were equally likely be diagnosed with a neurodegenerative disease.
Dr. Rowena Mobbs, a neurologist and director of the Australian CTE Biobank at Macquarie University, who was not involved with the research, commented: “The findings of this rigorous study into dementia risk in former international rugby union players strengthen existing evidence that CTE is caused by the accumulation of head injury, be it concussive or sub-concussive. We are yet to see the data emerge on CTE according to duration of play and age of commencement in rugby union, as has long been identified in American football or NFL but research is gearing up.”
The study noted a handful of limitations: all the players involved were male and the researchers were not able to determine whether a longer playing career was associated with an increased risk of neurodegenerative disease due to lack of data.
Call for change
To the authors, the conclusions from their and others’ research on the link between contact sport and MND is clear: “There is an immediate need for further, robust studies considering the specific association between sport, traumatic brain injury and risk of this rare, but uniformly fatal, outcome.”
The authors propose that changes are needed both during a player’s career and after, calling for efforts to reduce head injuries in training. “Interventions targeted towards risk mitigation among former rugby players with already accumulated head impact exposures might also be considered, including the development of specialist brain health clinics,” they write.
The study comes midway through a high-profile lawsuit by a group of ex-players against World Rugby, the Rugby Football Union and the Welsh Rugby Union. The group claims that negligent safety practices by authorities contributed to lifelong head injuries resulting from CTE.
Mobbs, for one, says it is time for sporting leaders to acknowledge the scale of the problem: “Sporting leadership should act now for the safety of the community and longevity of their own sports or face the consequences."
Russell ER, Mackay DF, Lyall D, et al. Neurodegenerative disease risk among former international rugby union players. J Neurol Neurosurg Psychiatry. 2022;0:1–7. doi:10.1136/jnnp-2022-329675