Former international rugby players are at a much higher risk of developing neurodegenerative disease, a major study into lifelong health led by the University of Glasgow has found.
The study, which is the largest undertaken on former rugby players to date, has revealed a doubling of the risks of a dementia diagnosis, and an over 10-fold risk of motor neurone disease diagnosis.
The research, published in the Journal of Neurology, Neurosurgery and Psychiatry, compared 412 former international rugby players in Scotland - all over the age of 30 in 2020 - with over 1,200 individuals from the general population.
While results did show age at death was slightly higher among former players, the comparative risk of neurodegenerative disease diagnosis was approximately two and a half times higher, with disease not varying by player position.
Former Wales second row Ryan Jones was diagnosed with early onset dementia in July of this year, aged just 41, while former Gloucester forward Ed Slater retired from professional rugby the same month following a diagnosis of motor neurone disease, aged 34.
Former Scotland and British and Irish Lions second row Doddie Weir was diagnosed with motor neurone disease in June 2017.
Prof Willie Stewart, lead consultant neuropathologist, said: "This latest work under our FIELD program of research demonstrates that risk of neurodegenerative disease is not isolated to former footballers, but also a concern for former rugby players.
"As such, this study provides further insight into the association between contact sports and neurodegenerative disease risk. Of particular concern are the data on motor neurone disease risk among our rugby players, which is even higher than that for former professional footballers.
"This finding requires immediate research attention to explore the specific association between rugby and the devastating condition of motor neurone disease."
The study also found that, although rugby union players had a higher risk of death overall from neurodegenerative disease, they were less likely to die of respiratory disease. And while deaths in former rugby players were lower than expected up to age 70, there was no difference to matched population controls over that age.
Dr Emma Russell, researcher at the University of Glasgow and first author on the study, added: "An important aspect of this work has been the ability to look across a range of health outcomes in former professional rugby players, allowing us to build a clear picture of health in this population.
"Our data show that, in contrast to our previous findings in former professional football players, rugby players do not appear to benefit from a reduced risk of death due to cardiovascular disease or cancer, suggesting the possibility of sport-specific influences on lifelong health."
Professor Stewart added: "Taking these new results in rugby, together with our pathology work and previous FIELD studies in football, the risk exposure of concern must remain repetitive head impacts and head injuries. As such, precautionary approaches should be adopted to reduce unnecessary head impacts and better manage head injuries across all contact sports."
Alzheimer's Research UK: Findings regarding rugby players concerning
Dr Susan Kohlhaas, director of research at Alzheimer's Research UK, said of the findings: "Rugby means so much to so many, it is a game that inspires, that brings people together from many cultures around the world, and one that is played by both men and women, at all levels up and down the country. But as with all contact sports, it has risks.
"While the benefits of physical exercise on brain and heart health are well known, multiple studies show links between traumatic brain injury and the development of dementia. Previous findings from this research team have also suggested that ex-professional footballers are at increased risk of neurodegenerative diseases.
"It's concerning to see research now identify former male rugby players as being at increased risk of dementia, and at particularly high risk of the neurodegenerative condition motor neurone disease.
"The research team point towards head impacts during the careers of rugby players having a role in the development of the diseases, however quantifying the number of head injuries fell out of the scope of this research study.
"While this is the biggest study of its kind into former male rugby players, there are still uncertainties over the exact size of the risk - for example, since Motor Neurone Disease is a rare condition, there were no cases of MND in the aged-match controls and so much larger studies are needed to paint a clearer picture.
"Interest in the links between participating in sport and risk of dementia is at an all-time high. Researchers, funders, stakeholders, and custodians of the sport must seize this moment to deliver new, coordinated research to give every person the best possible chance of living a dementia-free life."