The death of Neale Daniher and the heartbreaking diagnosis of Jai Arrow at just 30 years old has reignited one of the biggest and most uncomfortable debates in modern sport: are elite footballers more likely to develop motor neurone disease?
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 out of the blue the previous week, leaving rugby league stunned to its core.
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 the news breaking, attention turned to head knocks, repeated collisions and whether years of contact sport may have contributed to his condition.
But while researchers are increasingly concerned about links between contact sports and neurodegenerative disease, experts also stress one critical point: there is still no definitive proof that rugby league, rugby union or AFL directly cause MND.
NRL star Jai Arrow has retired aged just 30, with his devastating motor neurone disease diagnosis leaving rugby league fans shattered
Neale Daniher (pictured centre with his wife Jan and Anthony Albanese) raised millions through his FightMND charity before his death on Monday, aged 65
Arrow has vowed to ‘fight this b****’ for his daughter, family and fellow MND sufferers
That nuance is important, because while evidence of a possible link between the condition and contact sport is growing, so is confusion.
And 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.
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.
Carl Webb died aged 42 after a public and courageous four-year battle with motor neurone disease
Webb played 12 Origins for Queensland and became an inspiration during his MND fight
The emotional weight of those stories has inevitably 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 of the issue.
‘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.
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.
The review found 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 became public.
Doddie Weir became one of rugby’s most powerful MND advocates following his diagnosis in 2016
Rugby union star Lewis Moody revealed his MND diagnosis in 2025, reigniting debate around contact sports and neurodegenerative disease
‘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.
‘People are pivoting to Jai’s concussion injury, and it’s not about that.
‘It’s not about stopping a concussion from occurring, you can still get a concussion, but it’s stopping that exposure accumulation that’s important.’
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. The findings were striking.
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 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.
Importantly, researchers repeatedly cautioned that association does not equal proof.
Neale Daniher was named Australian of the Year in 2025
Daniher transformed his MND diagnosis into a national fundraising and awareness movement through FightMND
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,’ the organisation states.
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.
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.’
‘We know that MND is caused by a mixture of environment, lifestyle and genetics,’ Cole said.
‘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 they are 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. That 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.
And for players, families and sporting bodies alike, that uncertainty may be the most frightening part of all.
