A major University of Auckland-led study examining the long-term brain health of former high-level male rugby players in New Zealand has found higher rates of neurodegenerative disease compared to the general population.
And the study found that the higher the level of rugby played, the higher the rate of brain disorder risk.
Published on Friday in Sports Medicine, the study is part of Kumanu Tāngata: The Aftermatch Project, a research project designed to explore the long-term health and social outcomes of high-level male rugby players in Aotearoa New Zealand.
New Zealand Rugby (NZR) and the New Zealand Rugby Foundation said they welcomed its release.
Researchers analysed the health records of 12,861 men who played at provincial level or higher between 1950 and 2000, comparing them with 2.39 million men from the general population matched by age, ethnicity and birthplace.
The research showed about five in every 100 men in the general population had developed a neurodegenerative disease such as Alzheimer's, Parkinson's disease, and other related illnesses, by the end of the research follow-up period.
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This was closer to six in 100 for former provincial rugby players and eight in 100 for former international players.
The risks were higher for backline players, those with longer careers, and those who played more matches.
The research found no evidence of higher rates of these conditions, such as Alzheimer's, appearing earlier in life. Players who developed them typically showed symptoms between the ages of 70 and 79.
NZR chief executive Mark Robinson said the research was a vital step forward in the organisation's ongoing player welfare work, particularly around brain health and concussion.
"Having played the game at the highest level, I understand the demands rugby places on our players - that's why player welfare isn't just a priority for me, it's personal. These results will be concerning for some people. While we can't change the past, we acknowledge the impact rugby has had on some players and their whānau.
"Their experiences matter deeply and they continue to guide the work we're doing to improve player welfare and drive meaningful change across the game."
The organisation said the findings provided a strong evidence base for NZR to continue working together to keep improving player safety in line with the latest evidence, and ensuring all players had access to clear information to make informed decisions about their health. NZR said this includes "supporting former players affected by neurodegenerative conditions".
Last week former Tasman Mako captain, Māori All Black, and Highlanders Super Rugby flanker Shane Christie suddenly died at the age of 39.
Christie retired from professional rugby in 2017 due to severe post-concussion symptoms, and had become a passionate advocate for the better understanding and prevention of brain injuries in the sport. He had spoken publicly about his belief he was suffering from chronic traumatic encephalopathy (CTE), which is linked to repeated head trauma.
NZR said it acknowledged the recent passing of Christie.
"Our thoughts remain with his whānau, friends and former teammates at this difficult time. The release of this research was planned in coordination with our partners and the Sports Medicine journal. We believe it is important to proceed in an open and transparent way, ensuring the findings are shared to support greater understanding and ongoing improvements in player safety and wellbeing."
While the study provided robust evidence of an association between high-level rugby participation and later-life neurodevelopmental disorder (NDD) risk, the findings did not include women, lower-level players, or those whose careers began after 2000.
NZR said the way the game is played has changed in this time, with player welfare the driving factor. Stricter tackle laws, safer scrum techniques and enhanced medical protocols have all been introduced to reduce concussion risks and support long-term brain health.
In March 2025, NZR, the NZ Rugby Players Association (NZRPA), and New Zealand Rugby Foundation launched an enhanced Brain Health and Concussion Risk Management Plan. Key elements include law changes to reduce high-impact contact, improved Head Injury Assessment (HIA) protocols, and better access to specialist medical support. Concussion awareness programmes are also being rolled out across all levels of the game.
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New Zealand Rugby Foundation chief executive Lisa Kingi-Bon said Kumanu Tāngata reflected its ongoing commitment to supporting players beyond their time on the field.
"The Brain Health and Concussion [Risk] Plan builds on this by focusing on long-term wellbeing, informed care, and culturally responsive approaches. Together, these initiatives aim to strengthen how we support players throughout their journey."
Together, the three organisations say they remain committed to updating safety measures in line with the latest evidence, supporting former players affected by neurodegenerative conditions, and ensuring all players have access to clear, accessible information to make informed decisions about their health.
Kumanu Tāngata was funded and facilitated by World Rugby, New Zealand Rugby Foundation, NZR, Statistics New Zealand, and the University of Auckland Public Policy Institute.
This was the first of several studies within the project, with future research exploring broader health outcomes and the long-term benefits of playing rugby.
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