South Sydney forward Jai Arrow, 30, has revealed a devastating motor neurone disease (MND) diagnosis, effectively ending a decade-long career in the league.
Several other high-profile athletes have been diagnosed with the condition in recent years, including Australian rugby league player Carl Webb, who died in 2023, aged 42, after a battle with motor neurone disease and legendary English rugby league player Rob Burrow, who died in June 2024.
So, what is MND? And given the risk of head injuries in contact sports like NRL, is there an association between head trauma and the disease?
What is motor neurone disease?
MND is an umbrella term used to describe a class of diseases that affect nerve cells called motor neurons, whose job it is to carry messages from the brain to the muscles via the spinal cord.
These nerve cells are essential for movements like walking, swallowing, talking and breathing.
While MND affects each person differently, in terms of initial symptoms, rate and pattern of progression and survival time, those affected experience muscle weakness and wasting as nerves become damaged and start to die.
About 800 Australians are diagnosed with MND each year, while the disease is responsible for roughly one in every 200 deaths annually.
The average survival time after diagnosis is 2½ years, but a minority (about 5 to 10 per cent) will survive for more than 10 years.
Liam O’Meara, MND NSW chief executive, whose father died from the disease, thinks there needs to be greater awareness about its devastating impacts.
“It’s important to note that whilst it may seem like a rare disease, it’s more of an uncommon disease,” he says. “It’s possibly the cruellest disease you can get.
“Unfortunately, it does take people like Jai Arrow to start to draw more attention.”
What causes MND, and is there a connection with head injuries?
“Ten per cent of motor neurone disease is caused by faulty genes, and that’s passed on from parent to child,” says Professor Dominic Rowe, a clinical neurologist and researcher at Macquarie University who specialises in neuro-degenerative diseases.
Sporadic motor neurone disease, which accounts for about 90 per cent of all MND cases, is thought to be triggered by environmental factors, says Rowe. These include chemicals pervasive in the environment like insecticides, pesticides, fungicides and herbicides.
Those living in rural Australia, for example, are 40 per cent more likely to die from motor neurone disease.
“We think that this is co-location of population with agriculture and exposure to chemicals in an environment that damages special cells like motor neurone,” says Rowe.
Other co-associations include environmental lead deposition, organic solvents and electrical injury, says Rowe.
“But we’re very concerned about the exposure in agriculture and in some veterinary medicines too.”
Another suspected risk factor for MND is head injury, he says, which is relatively common in contact sports like rugby league, rugby union, AFL and soccer.
According to a 2024 position statement from the Australian Institute of Sport’s Concussion and Brain Health, an incidence of 15.4 diagnosed concussions per 1000 hours of match play was reported during the 2019 NRL season.
Another report from the Rugby League Players’ Association last year found 60 per cent of NRL players continued to train after suffering a suspected concussion at training.
But concussion is also common in non-contact sports like marathon running and cycling.
“It’s not necessarily a smoking gun,” says Rowe.
“Head injury itself doesn’t cause motor neurone disease, but what it does, we think, is disrupt the very special protective barrier called the blood-brain barrier that protects your brain from the agents in the environment that may damage such sensitive cells like motor neurons.”
One 2022 study from New Zealand researchers found evidence that “repeated head injury with concussion, playing sports in general, and playing football (soccer) in particular, are associated with an increased risk of MND”. Its findings also suggested a link between emotional trauma resulting from physical abuse in childhood, and MND.
Still, O’Meara emphasises more research is needed.
“That is probably the most devastating thing … is that we don’t have the answers. We don’t know why,” he says.
What are the first signs of MND?
MND is not a linear disease, and early signs depends on where the disease starts, explains Rowe.
“If the disease starts in the base of your brain, what’s called the brain stem, then patients often have slurred speech as their first symptom,” he says. “If it starts in their spinal cord, then that produces weakness in their hands or arms.”
O’Meara, describing the disease as “insidious”, says symptoms commonly start with the outer extremities, with something like tremors, but are highly dependent on the type of MND.
Is there any treatment for MND?
There is currently no known cure for motor neurone disease, and for those with sporadic MND, its most common iteration, “we don’t yet have a therapy that dramatically changes outcome”, says Rowe.
But for those with a genetic mutation of MND called SOD1, Australian researchers last year developed a breakthrough therapy that shows promise for treatment.
MND is not a notifiable disease – meaning it does not need to be reported to government health authorities – something O’Meara says MND Australia is advocating for to change as it would improve data collection.
“That’s a step in the right direction because we’ll start getting the information we need to make better informed decisions,” he says.
More robust data will not only help fund research – O’Meara says some estimates say we are 10 to 15 years from finding a cure – but also bolster funding for support for those already living with the disease, particularly in aged care.
“Until there is a cure, we really need a lot more funding to be on care and services right now. It’s a very costly disease. So there needs to be more focus on helping people with the disease right now.”
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