The brain disease at the centre of a $US500m-plus class action settlement between the NFL and thousands of retired American football players has been linked to the deaths of two former rugby league players.
New findings -- uncovered by researchers and clinicians from the University of Sydney's Brain and Mind Centre, Royal Prince Alfred Hospital and NSW Health Pathology and published in the international neuropathology journal Acta Neuropathologica Communications -- show evidence that the two players were afflicted by Chronic Traumatic Encephalopathy, or CTE.
The players -- who were not named by the report -- both ran out in more than 150 first-grade games, and had their brains examined after death. It is believed the findings are the first time CTE has been linked to rugby league.
"The changes in the two brains were distinctive, definitive, and met consensus diagnostic criteria for CTE," lead author Clinical Associate Professor Michael Buckland, head of the RPA Neuropathology Department and head of the Molecular Neuropathology Program at the Brain and Mind Centre, told News Limited.
"I have looked at about 1000 brains over the last 10 years, and I have not seen this sort of pathology in any other case before.
"The fact that we have now seen these changes in former rugby league players indicates that they, and likely other Australian collision sports players, are not immune to CTE, a disease that has gained such high profile in the United States."
This is the first confirmed case of CTE in rugby league, although former Manly rugby union player Barry Taylor was the only other confirmed case of CTE identified in an Australian sportsperson.
In 2018 research, conducted by concussion expert Dr Alan Pearce, 25 former NRL players were studied and compared to 25 men of a similar age with no history of concussion or brain injury. The NRL players returned poorer results tasks relating to memory, short-term learning and attention, reaction time and fine motor skills.
CTE was first discovered in the U.S. by Doctor Bennet Omalu in 2002 but it took until 2016 for the NFL to publicly acknowledge a connection between the sport and the illness.
It followed a groundbreaking class-action lawsuit settlement between the league and thousands of former players, who were provided with payments of up to $5 million each due to the impact of repeated head trauma.
Historically the term chronic traumatic encephalopathy was used synonymously with 'punch-drunk' to describe the neurological deficits of ex-boxers thought due to repeated blows to the head. It is a regressive neurological condition found in athletes, military veterans and others with a history of repetitive brain trauma, specifically concussions.
The discovery of the CTE, and the strong denials from the NFL that the disease was linked to the high-impact sport, formed the basis of the 2015 movie "Concussion."