This Popular Sport Is Linked to an Increased Risk of Dementia

Researchers at the University of Auckland have found a link between playing high-level rugby and an increased risk of developing dementia.

A new study from the University of Auckland has found that men who played rugby at a high level in New Zealand face a 22 percent greater likelihood of developing Alzheimer’s disease or other dementias later in life compared with men in the general population.

The research was jointly led by Dr. Stephanie D’Souza, a senior lecturer at the University’s COMPASS Research Centre within the Faculty of Arts and Education, and Dr. Ken Quarrie from New Zealand Rugby.

To investigate the long-term impact of playing the sport, the team analyzed health records from nearly 13,000 men who had competed in provincial or higher-level rugby between 1950 and 2000. Their outcomes were compared against a group of 2.4 million New Zealand men of the same age, ethnicity, and birthplace.

Over the 35-year follow-up period (1988 to 2023), about 52 men per 1,000 in the general population were either diagnosed with or died from a neurodegenerative condition. Among former rugby players, however, the figure rose to 65 per 1,000, according to lead author PhD student Francesca Anns.

“This is an extra 13 cases per 1,000 people over the study period, or around four extra neurodegenerative disease cases per year, given the size of the player cohort,” she says.

Player Positions and Duration of Play

And she says both international/professional and provincial/first-class amateur players had higher risks than the general population, although the risks were greater at the higher playing level.

“Our analysis also showed that players in backline positions had greater risks than forwards, with the risk for backs increasing further the longer they played or the more matches they played, a pattern not observed for forwards.”

Anns says the increased risk of disease typically becomes apparent from the age of 70 onwards, with no evidence of earlier-onset illness.

Co-lead investigator Dr Stephanie D’Souza says these results are consistent with research into other collision sports from the US, Scotland, and Italy, but the effect sizes in their study were slightly smaller than most previous reports.

“That may reflect differences in how the study was designed,” she says, “including the size and make up of our comparison group, the fact that our study included both provincial and international players, rather than only elite professionals, and how cases were identified, as well as differences in how rugby was played in New Zealand over the decades we studied.”

Implications for Player Safety

The study is part of the Kumanu Tāngata project, which is focused on investigating the long-term health outcomes of first-class rugby players using de-identified linked data, which means names are removed.

It adds to growing evidence linking collision sports with later-life brain health risks, believed to be due to exposure to head knocks, says D’Souza.

“While the research can’t prove causation, the consistent pattern across multiple studies strengthens the case for a connection. In this study, higher risks were seen in players who competed at the international or professional level, as compared to those who only played provincially, and for backs whose risk increased with more years and matches played.”

She says these patterns showing higher risk with both greater intensity and longer duration of play suggest a possible ‘dose-response’ relationship.

“The position differences also indicate that the nature of contact, not just the number of head impacts, may be important in understanding risk.”

The study’s authors recommend that collision sports organizations limit player exposure to head impacts and manage suspected concussions proactively, while continuing to communicate openly about both the benefits and risks of participation in sports like rugby.

Reference: “Neurodegenerative Diseases in Male Former First-Class New Zealand Rugby Players” by Francesca Anns, Kenneth L. Quarrie, Barry J. Milne, Chao Li, Andrew J. Gardner, Ian R. Murphy, Evert Verhagen, Craig Wright, Susan M. B. Morton, Thomas Lumley, Lynette Tippett and Stephanie D’Souza, 4 September 2025, Sports Medicine.
DOI: 10.1007/s40279-025-02299-y

This study was supported by World Rugby Limited and the New Zealand Rugby Foundation. Statistics New Zealand, and its staff granted researchers access to the Integrated Data Infrastructure (IDI), a large research database which holds anonymous microdata about people and households in New Zealand.

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