The recent death of Neale Daniher and the heartbreaking motor neurone disease (MND) diagnosis of Jai Arrow at just 30 years old have reignited one of the most uncomfortable debates in modern sport: are elite footballers more likely to develop MND?
On Monday, Daniher's family announced that the Essendon and Melbourne legend had lost his battle with the incurable condition after being diagnosed in 2013. Arrow's emotional retirement announcement came the previous week, leaving the rugby league world stunned. The former Queensland Maroons forward was still in the prime of his career, having played 178 NRL games for the Brisbane Broncos, Gold Coast Titans, and South Sydney Rabbitohs.
Within hours of Arrow's news, attention turned to head knocks, repeated collisions, and whether years of contact sport may have contributed to his condition. However, while researchers are increasingly concerned about links between contact sports and neurodegenerative disease, experts stress a critical point: there is still no definitive proof that rugby league, rugby union, or AFL directly cause MND.
That nuance is important because while evidence of a possible link between MND and contact sport is growing, so is confusion. Scientists say the real story is far more complicated than one concussion or tackle gone wrong. Researchers now believe the answer may lie in the accumulation of thousands of smaller impacts footballers suffer over many years, mixed with genetics, environmental exposure, training loads, and possibly even extreme physical exertion itself.
Historical Context of MND in Sport
The concern around elite athletes and MND did not begin with Arrow. Former Broncos, Cowboys, and Maroons star Carl Webb died in 2023 aged just 42 after a public battle with the disease, and former Balmain Tigers star Scott Gale died from MND in 2004, aged 39. In rugby union, George 'Doddie' Weir, Ed Slater, and Lewis Moody have all become prominent faces associated with the disease. The AFL has its own deeply emotional connection through Neale Daniher, who was diagnosed in 2013 and became one of the country's leading MND advocates through FightMND. Daniher's advocacy work led to him being named Australian of the Year in 2025.
The emotional weight of those stories has intensified public concern, but scientists say the evidence remains incomplete. 'The simple answer is we do not know yet,' the MND Association UK stated in its official review. 'There is not enough evidence to show there is a strong link.' The organisation says current evidence suggests a combination of environmental, lifestyle, and genetic factors likely interact before the disease develops.
Research Findings and Expert Opinions
Still, researchers have found enough concerning patterns that many believe the possibility of a link can no longer be dismissed. A landmark review by the British Journal of Sports Medicine examined 45 separate studies into sport-related trauma and MND, finding that professional athletes in football codes may be four to 15 times more likely to develop the disease.
Professor Alan Pearce from Swinburne University of Technology believes the public often misunderstands the risk. 'It gives the impression that it's all about the big hit,' Pearce said after Arrow's diagnosis. 'We need to get people to understand it's smaller hits over a longer period that we need to deal with. That's what the science is now telling us.' He emphasised that it is not about stopping a concussion from occurring but stopping that exposure accumulation.
That idea – cumulative exposure rather than one catastrophic incident – is becoming central to modern research. One of the strongest studies so far came from New Zealand in 2022, where researchers analysed 321 MND patients and 605 control subjects. Participants who reported two concussions had an odds ratio of 4.01 for developing MND, while those with three or more head injuries also showed elevated risk. The study also found that people who played sport continuously through childhood and adulthood had higher MND risk, while football players participating for more than 12 years showed more than double the risk compared to non-players.
However, researchers repeatedly cautioned that association does not equal proof. The study itself stated the evidence remained 'largely inconclusive'. The MND Association UK echoes that warning: 'While studies carried out to date suggest a correlation between these professional sports and MND they do not demonstrate causation.' That distinction is critical medically and legally. Correlation means researchers are observing patterns; causation would mean proving the sport itself directly causes the disease. Scientists say they are not there yet.
The Complexity of MND
Part of the challenge is that MND remains one of medicine's least understood illnesses. The disease attacks motor neurones – nerve cells controlling movement, speech, swallowing, and breathing. Over time, muscles progressively weaken and waste away. There is currently no cure, and the lifetime risk is estimated at roughly one in 300. Researchers also believe genetics may heavily influence who becomes vulnerable.
Dr Nick Cole told ESPN Rugby there was 'no concrete, definitive link between rugby and MND.' He said, 'We know that MND is caused by a mixture of environment, lifestyle, and genetics. Sport could be one of the contributing factors, but there are many other subjects within the biology of MND that we are investigating to find the effective treatments we need.'
Researchers are now examining whether intense physical exertion itself may also play a role. Scientists from the University of Sheffield recently found evidence suggesting extreme exercise in men may increase MND risk and lead to earlier onset in genetically susceptible individuals. Again, the findings are far from definitive but enough to alarm many experts.
Pearce has advocated reducing contact training and delaying children from participating in contact sports until age 14. Across world sport, administrators are already responding. The AFL, NRL, rugby union, and soccer have all introduced stricter concussion protocols in recent years. Junior sport has also shifted dramatically, with many programs reducing tackling or contact exposure during training. Yet some researchers believe training itself may still represent a hidden problem. Athletes can experience thousands of subconcussive impacts across careers without ever suffering a diagnosed concussion, which is now emerging as a major scientific focus.
Arrow's diagnosis has brought those fears crashing back into public view because of how young he is. 'For me it was the age that Jai has been diagnosed that's concerning,' Pearce said. 'But when you have someone like Jai, who's 30, that's when it hits home that this is something we need to talk about in a controlled manner.'
For now, though, the science remains unsettled. Even the major medical organisations investigating the issue continue urging caution. A 2025 independent report into professional athletes and MND concluded the evidence base was 'not sufficiently clear nor consistent enough' to formally establish a proven causal link. That means no expert can currently say rugby league caused Jai Arrow's illness, but equally, few scientists are dismissing the possibility anymore. Instead, researchers across Australia, New Zealand, and Europe are now racing to understand whether repeated collisions, heavy training loads, genetic predisposition, and years of physical punishment may combine in dangerous ways. For players, families, and sporting bodies alike, that uncertainty may be the most frightening part of all.
