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Neurodegenerative Diseases in Male Former First-Class New Zealand Rugby Players
Open accessAbstract
Background: Growing concern surrounds the risk of neurodegenerative diseases in high-level collision sports, but research on Rugby Union's connection to these diseases is limited. Objective: This study sought to examine the long-term neurodegenerative disease risk associated with participation in high-level Rugby Union (‘rugby’), utilising whole-population administrative records. Methods: This retrospective cohort study in New Zealand compared males born between 1920 and 1984 who were active in high-level (provincial or higher) rugby between 1950 and 2000 ( n = 12,861) with males from the general population ( n = 2,394,300), matched by age, ethnicity, and birthplace. We used Cox proportional hazards models to assess risks of Alzheimer's disease, Parkinson's disease, motor neuron disease, and other dementias, ascertained using mortality and hospitalisation records from January 1988 to June 2023. Results: A higher percentage of rugby players (6.5%) than males in the general population (5.2%) developed neurodegenerative diseases, with hazard ratios indicating players showed increased risks for any neurodegenerative disease (1.22; 95% confidence interval [CI] 1.14–1.30), Alzheimer's disease (1.61; 95% CI 1.42–1.83), and other dementias (1.23; 95% CI 1.14–1.33). Significant differences were not observed for Parkinson’s disease (1.05; 95% CI 0.89–1.22) and motor neuron disease (1.16; 95% CI 0.83–1.63). In general, this increased risk among players compared to the general population began around the ages of 70–79 years. Compared to the general population, small to moderate increased risks of any neurodegenerative disease were observed for a backline playing position, provincial and/or amateur players, international and/or professional players, participation in ≥ 2 years of play, and participation in five or more matches. Conclusions: High-level rugby participation amongst males in New Zealand is associated with a small to moderate increase in neurodegenerative disease rates compared to the general population.
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In that New Zealand cohort, high-level rugby participation was associated with an increased risk of motor neuron disease (HR 1.16).
“High-level rugby participation was associated with increased neurodegenerative disease risk (HR 1.22), including Alzheimer's disease (HR 1.61) and MND (HR 1.16).”
From History of Head Injury and Risk of Amyotrophic Lateral Sclerosis: An Updated Comprehensive Systematic Review with Meta-Analysis of 5,033,215 Participants (2026) · cites this paper as Anns et al. 2025
The Results (Comparisons Between Rugby Players and the General Population) report the quoted MND HR of 1.16, but explicitly say players were not more likely to be diagnosed with MND; its 95% CI of 0.83–1.63 includes 1. The Abstract Results likewise state that the difference was not significant. Thus the number is correct, but presenting MND as an increased-risk finding contradicts the paper’s conclusion for players overall. (LLM, conf=0.90)
Checked by a reasoning model — may be wrong.
Experimental — accuracy not yet measuredIn a New Zealand retrospective cohort of high-level rugby players, high-level rugby participation was associated with an increased risk of neurodegenerative disease (HR 1.22).
“High-level rugby participation was associated with increased neurodegenerative disease risk (HR 1.22), including Alzheimer's disease (HR 1.61) and MND (HR 1.16).”
From History of Head Injury and Risk of Amyotrophic Lateral Sclerosis: An Updated Comprehensive Systematic Review with Meta-Analysis of 5,033,215 Participants (2026) · cites this paper as Anns et al. 2025
The Abstract’s Results report increased risk of any neurodegenerative disease (HR 1.22) and Alzheimer’s disease (HR 1.61) among male New Zealand rugby players. The citing sentence also includes MND as an increased risk, but the paper says its HR of 1.16 was not a significant difference (95% CI 0.83–1.63). Page numbers were not provided in our copy. (LLM, conf=0.90)
Experimental — accuracy not yet measuredIn that New Zealand cohort, neurodegenerative disease risks were higher among backline players.
“Risks were higher among backline players.”
From History of Head Injury and Risk of Amyotrophic Lateral Sclerosis: An Updated Comprehensive Systematic Review with Meta-Analysis of 5,033,215 Participants (2026) · cites this paper as Anns et al. 2025
In that New Zealand cohort, high-level rugby participation was associated with an increased risk of Alzheimer's disease (HR 1.61).
“High-level rugby participation was associated with increased neurodegenerative disease risk (HR 1.22), including Alzheimer's disease (HR 1.61) and MND (HR 1.16).”
From History of Head Injury and Risk of Amyotrophic Lateral Sclerosis: An Updated Comprehensive Systematic Review with Meta-Analysis of 5,033,215 Participants (2026) · cites this paper as Anns et al. 2025
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1 retracted
Dementia prevention, intervention, and care: 2020 report of the Lancet Commission
Livingston, G., Huntley, J., Sommerlad, A., Ames, D., Ballard, C., Banerjee, S., Brayne, C., Burns, A., Cohen-Mansfield, J., Cooper, C., et al. (2020) · The Lancet · doi:10.1016/s0140-6736(20)30367-6 · Cited by 10,430
RetractedDementia prevention, intervention, and care: 2024 report of the Lancet standing Commission
Livingston, G., Huntley, J., Liu, K. Y., Costafreda, S. G., Selbæk, G., Alladi, S., Ames, D., Banerjee, S., Burns, A., Brayne, C., et al. (2024) · The Lancet · doi:10.1016/s0140-6736(24)01296-0 · Cited by 3,860 · cited 2×
“Fourteen potential modifiable risk factors have recently been described by the Lancet Commission on dementia, one of which is traumatic brain injury [22].”
Health benefits of physical activity: a systematic review of current systematic reviews
Warburton, D. E. R., & Bredin, S. S. D. (2017) · Current Opinion in Cardiology · doi:10.1097/hco.0000000000000437 · Cited by 2,410
Rebar, A. L., Stanton, R., Geard, D., Short, C., Duncan, M. J., & Vandelanotte, C. (2015) · Health Psychology Review · doi:10.1080/17437199.2015.1022901 · Cited by 1,323
Neurodegenerative causes of death among retired National Football League players
Lehman, E. J., Hein, M. J., Baron, S. L., & Gersic, C. M. (2012) · Neurology · doi:10.1212/wnl.0b013e31826daf50 · Cited by 638
Neurodegenerative disease mortality among former professional soccer players
Mackay, D. F., Russell, E. R., Stewart, K., MacLean, J. A., Pell, J. P., & Stewart, W. (2019) · New England Journal of Medicine · doi:10.1056/nejmoa1908483 · Cited by 483
Chronic traumatic encephalopathy - confusion and controversies
Smith, D. H., Johnson, V. E., Trojanowski, J. Q., & Stewart, W. (2019) · Nature Reviews Neurology · doi:10.1038/s41582-018-0114-8 · Cited by 166
Lee, E. B., Kinch, K., Johnson, V. E., Trojanowski, J. Q., Smith, D. H., & Stewart, W. (2019) · Acta Neuropathologica · doi:10.1007/s00401-019-02030-y · Cited by 157
Flagged first, then by citations
Research works printed but not linked: 51
- Prien A, Grafe A, Rössler R, Junge A, Verhagen E. Epidemiology of head injuries focusing on concussions in team contact sports: a systematic review. Sports Med. 2018;48:953–69. · DOI
- Gardner RC, Burke JF, Nettiksimmons J, Kaup A, Barnes DE, Yaffe K. Dementia risk after traumatic brain injury vs nonbrain trauma: the role of age and severity. JAMA Neurol. 2014;71:1490–7. · DOI · Paper page
- Godbolt AK, Cancelliere C, Hincapié CA, Marras C, Boyle E, Kristman VL, et al. Systematic review of the risk of dementia and chronic cognitive impairment after mild traumatic brain injury: results of the International Collaboration on Mild Traumatic Brain Injury Prognosis. Arch Phys Med Rehabil. 2014;95:S245–56. · DOI
- McKee AC, Cantu RC, Nowinski CJ, Hedley-Whyte ET, Gavett BE, Budson AE, et al. Chronic traumatic encephalopathy in athletes: progressive tauopathy after repetitive head injury. J Neuropathol Exp Neurol. 2009;68:709–35. · DOI · Paper page
- Asken BM, Sullan MJ, DeKosky ST, Jaffee MS, Bauer RM. Research gaps and controversies in chronic traumatic encephalopathy: a review. JAMA Neurol. 2017;74:1255–62. · DOI · Paper page
- LeClair J, Weuve J, Fox MP, Mez J, Alosco ML, Nowinski C, et al. Relationship between level of American football playing and diagnosis of chronic traumatic encephalopathy in a selection bias analysis. Am J Epidemiol. 2022;191:1429–43. · DOI
- Batty GD, Frank P, Kujala UM, Sarna SJ, Valencia-Hernández CA, Kaprio J. Dementia in former amateur and professional contact sports participants: population-based cohort study, systematic review, and meta-analysis. eClin Med. 2023;61: 102056.
- Iverson GL, Castellani RJ, Cassidy JD, Schneider GM, Schneider KJ, Echemendia RJ, et al. Examining later-in-life health risks associated with sport-related concussion and repetitive head impacts: a systematic review of case-control and cohort studies. Br J Sports Med. 2023;57:810–24. · DOI
- Orhant E, Carling C, Chapellier J-F, Marchand J-L, Pradat P-F, Elbaz A, et al. A retrospective analysis of all-cause and cause-specific mortality rates in French male professional footballers. Scand J Med Sci Sports. 2022;32:1389–99. · DOI
- Ueda P, Pasternak B, Lim C-E, Neovius M, Kader M, Forssblad M, et al. Neurodegenerative disease among male elite football (soccer) players in Sweden: a cohort study. Lancet Public Health. 2023;8: e256–65. · DOI
- McKee AC, Stein TD, Nowinski CJ, Stern RA, Daneshvar DH, Alvarez VE, et al. The spectrum of disease in chronic traumatic encephalopathy. Brain. 2013;136:43–64. · DOI · Paper page
- Smith DH, Johnson VE, Stewart W. Chronic neuropathologies of single and repetitive TBI: substrates of dementia? Nat Rev Neurol. 2013;9:211–21. · DOI · Paper page
- Chen GX, Douwes J, van den Berg L, Pearce N, Kromhout H, Glass B, et al. Occupational exposures to pesticides and other chemicals: a New Zealand motor neuron disease case–control study. Occup Environ Med. 2022;79:412–20. · DOI
- Castanedo-Vazquez D, Bosque-Varela P, Sainz-Pelayo A, Riancho J. Infectious agents and amyotrophic lateral sclerosis: another piece of the puzzle of motor neuron degeneration. J Neurol. 2019;266:27–36. · DOI · Paper page
- Asken BM, Sullan MJ, Snyder AR, Houck ZM, Bryant VE, Hizel LP, et al. Factors influencing clinical correlates of chronic traumatic encephalopathy (CTE): a review. Neuropsychol Rev. 2016;26:340–63. · DOI
- Cairns DM, Smiley BM, Smiley JA, Khorsandian Y, Kelly M, Itzhaki RF, et al. Repetitive injury induces phenotypes associated with Alzheimer’s disease by reactivating HSV-1 in a human brain tissue model. Sci Signal. 2025;18: eado6430. · DOI
- Williams S, Robertson C, Starling L, McKay C, West S, Brown J, et al. Injuries in elite men’s rugby union: an updated (2012–2020) meta-analysis of 11,620 match and training injuries. Sports Med. 2022;52:1127–40. · DOI
- Van Pelt KL, Puetz T, Swallow J, Lapointe AP, Broglio SP. Data-driven risk classification of concussion rates: a systematic review and meta-analysis. Sports Med. 2021;51:1227–44. · DOI
- McMillan TM, McSkimming P, Wainman-Lefley J, Maclean LM, Hay J, McConnachie A, et al. Long-term health outcomes after exposure to repeated concussion in elite level: rugby union players. J Neurol Neurosurg Psychiatry. 2017;88:505–11. · DOI
- Hume PA, Theadom A, Lewis GN, Quarrie KL, Brown SR, Hill R, et al. A comparison of cognitive function in former rugby union players compared with former non-contact-sport players and the impact of concussion history. Sports Med. 2017;47:1209–20. · DOI
- Hume PA, Quarrie KL, Lewis GN, Theadom A. Nz-rugbyhealth study: self-reported injury experience and current health of former rugby union and non-contact sport players. Sports Med. 2022;52:1701–13. · DOI
- Hind K, Konerth N, Entwistle I, Theadom A, Lewis G, King D, et al. Cumulative sport-related injuries and longer term impact in retired male elite- and amateur-level rugby code athletes and non-contact athletes: a retrospective study. Sports Med. 2020;50:2051–61. · DOI
- Davies MAM, Judge DA, Delmestri A, Kemp PTS, Stokes KA, Arden NK, et al. Health amongst former rugby union players: a cross-sectional study of morbidity and health-related quality of life. Sci Rep. 2017;7:11786. · DOI
- Decq P, Gault N, Blandeau M, Kerdraon T, Berkal M, ElHelou A, et al. Long-term consequences of recurrent sports concussion. Acta Neurochir. 2016;158:289–300. · DOI
- Cunningham J, Broglio S, Wilson F. Influence of playing rugby on long-term brain health following retirement: a systematic review and narrative synthesis. BMJ Open Sport Exerc Med. 2018;4: e000356. · DOI
- Zimmerman KA, Laverse E, Samra R, Yanez Lopez M, Jolly AE, Bourke NJ, et al. White matter abnormalities in active elite adult rugby players. Brain Commun [Internet]. 2021. https://doi.org/10.1093/braincomms/fcab133. · DOI
- Guell X, Arnold Anteraper S, Gardner AJ, Whitfield-Gabrieli S, Kay-Lambkin F, Iverson GL, et al. Functional connectivity changes in retired Rugby League players: a data-driven functional magnetic resonance imaging study. J Neurotrauma. 2020;37:1788–96. · DOI
- Sharma A, Hind K, Hume P, Singh J, Neary JP. Neurovascular coupling by functional near infra-red spectroscopy and sport-related concussion in retired rugby players: the UK Rugby Health Project. Front Hum Neurosci [Internet]. 2020. https://doi.org/10.3389/fnhum.2020.00042. · DOI
- Russell ER, Mackay DF, Lyall D, Stewart K, MacLean JA, Robson J, et al. Neurodegenerative disease risk among former international rugby union players. J Neurol Neurosurg Psychiatry. 2022;93:1262–8. · DOI
- Quarrie KL, Hopkins WG, Anthony MJ, Gill ND. Positional demands of international rugby union: evaluation of player actions and movements. J Sci Med Sport. 2013;16:353–9. · DOI
- Tooby J, Woodward J, Tucker R, Jones B, Falvey É, Salmon D, et al. Instrumented mouthguards in elite-level men’s and women’s rugby union: the incidence and propensity of head acceleration events in matches. Sports Med. 2023. https://doi.org/10.1007/s40279-023-01953-7. · DOI
- Tucker R, Raftery M, Fuller GW, Hester B, Kemp S, Cross MJ. A video analysis of head injuries satisfying the criteria for a head injury assessment in professional Rugby Union: a prospective cohort study. Br J Sports Med. 2017;51:1147–51. · DOI
- Quarrie KL, Hopkins WG. Tackle injuries in professional rugby union. Am J Sports Med. 2008;36:1705–16. · DOI
- Bussey MD, Salmon D, Romanchuk J, Nanai B, Davidson P, Tucker R, et al. Head acceleration events in male community rugby players: an observational cohort study across four playing grades, from under-13 to senior men. Sports Med. 2024;54:517–30. · DOI
- Russell ER, Mackay DF, Stewart K, MacLean JA, Pell JP, Stewart W. Association of field position and career length with risk of neurodegenerative disease in male former professional soccer players. JAMA Neurol. 2021;78:1057–63. · DOI
- Patricios JS, Schneider KJ, Dvorak J, Ahmed OH, Blauwet C, Cantu RC, et al. Consensus statement on concussion in sport: the 6th international conference on concussion in Sport-Amsterdam, October 2022. Br J Sports Med. 2023;57(11):695–711. · DOI
- Milne B, Atkinson J, Blakely T, Day H, Douwes J, Gibb S, et al. Data resource profile: the New Zealand integrated data infrastructure (IDI). Int J Epidemiol. 2019. https://doi.org/10.1093/ije/dyz014. · DOI
- D’Souza S, Milne BJ, Li C, Anns F, Gardner A, Lumley T, et al. Kumanu Tāngata: the aftermatch study—protocol to examine the health outcomes of high-level male rugby union players using linked administrative data. BMJ Open Sport Exerc Med. 2024;10: e001795. · DOI
- von Elm E, Altman DG, Egger M, Pocock SJ, Gøtzsche PC, Vandenbroucke JP. The strengthening the reporting of observational studies in epidemiology (STROBE) statement: guidelines for reporting observational studies. Lancet. 2007;370:1453–7. · DOI · Paper page
- Akers C. New Zealand Rugby Register 1870–2015: the players, referees and administrators in First-Class Rugby. Palmerston North: New Zealand Rugby Museum; 2016.
- Quarrie K, Gianotti S, Murphy I. Injury risk in New Zealand Rugby Union: a nationwide study of injury insurance claims from 2005 to 2017. Sports Med. 2020;50:415–28. · DOI
- Walesby KE, Exeter DJ, Gibb S, Wood PC, Starr JM, Russ TC. Prevalence and geographical variation of dementia in New Zealand from 2012 to 2015: brief report utilising routinely collected data within the Integrated Data Infrastructure. Australas J Ageing. 2020;39:297–304. · DOI
- Haneuse S. Time-to-event analysis. Modern epidemiology. 4th ed. Philadelphia: Wolters Kluwer; 2021. p. 531–62.
- Daneshvar DH, Mez J, Alosco ML, Baucom ZH, Mahar I, Baugh CM, et al. Incidence of and mortality from amyotrophic lateral sclerosis in National Football League athletes. JAMA Netw Open. 2021;4: e2138801. · DOI
- Chen GX, Douwes J, van den Berg LH, Glass B, McLean D, ’t Mannetje AM. Sports and trauma as risk factors for motor neurone disease: New Zealand case–control study. Acta Neurol Scand. 2022;145:770–85. · DOI
- LoBue C, Wadsworth H, Wilmoth K, Clem M, Hart J, Womack KB, et al. Traumatic brain injury history is associated with earlier age of onset of Alzheimer disease. Clin Neuropsychol. 2017;31:85–98. · DOI · Paper page
- Schaffert J, LoBue C, White CL, Chiang H-S, Didehbani N, Lacritz L, et al. Traumatic brain injury history is associated with an earlier age of dementia onset in autopsy-confirmed Alzheimer’s disease. Neuropsychology. 2018;32:410–6. · DOI · Paper page
- Gaetz M. The multi-factorial origins of Chronic Traumatic Encephalopathy (CTE) symptomology in post-career athletes: the athlete post-career adjustment (AP-CA) model. Med Hypotheses. 2017;102:130–43. · DOI
- European Parliament. Directorate General for Parliamentary Research Services. The precautionary principle: definitions, applications and governance: in depth analysis. [Internet]. LU: Publications Office; 2016 [cited 2023 Jul 26]. https://doi.org/10.2861/821468. · DOI
- Quarrie KL, Hopkins WG. Changes in player characteristics and match activities in Bledisloe Cup rugby union from 1972 to 2004. J Sports Sci. 2007;25:895–903. · DOI
- Romero JP, Benito-León J, Louis ED, Bermejo-Pareja F. Under reporting of dementia deaths on death certificates: a systematic review of population-based cohort studies. JAD. 2014;41:213–21. · DOI
Cited by
Sorted by citations
Hawas, Y., Abdelmageed, A., Messak, M., Ziada, A., Gamal, M., Ghanem, T. I. E., Abdelwahab, M. M., Meshref, M., & Kashbour, M. O. (2026) · Neuroepidemiology · doi:10.1159/ned/adwag050
Metadata
- Authors
- Anns, F., Quarrie, K. L., Milne, B. J., Li, C., Gardner, A. J., Murphy, I. R., Verhagen, E., Wright, C., Morton, S. M. B., Lumley, T., Tippett, L., & D’Souza, S.
- Affiliations
- University of Auckland (NZ)
- Reserve Bank of New Zealand (NZ)
- The University of Sydney (AU)
- Illawarra Shoalhaven Local Health District (AU)
- Amsterdam University Medical Centers (NL)
- University of Technology Sydney (AU)
- Corresponding author
- D’Souza, Stephanie
- ORCID
- Venue
- Sports Medicine
- Published
- 2025-09-04
- Volume
- 56
- Issue
- 2
- Pages
- 543-558
- ISSN
- 0112-1642 (ISSN-L)
- 1179-2035
- PMC
- PMC12982275
- OpenAlex
- W4413985072
- Cited by
- 6
- References
- 8
- Citations by year
- 2026: 5 · 2025: 1
- FWCI
- 3.22
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Locations
- Sports Medicine (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- Pure Amsterdam UMC (acceptedVersion, other-oa)
- VUBIR (Vrije Universiteit Brussel) (submittedVersion)
- Funders
- World Rugby Limited
- New Zealand Rugby Foundation (G-2004-00963)
- University of Auckland
- Topics
- Health Sciences › Medicine › Clinical Neurology › Traumatic Brain Injury Research
- Health Sciences › Medicine › Orthopedics and Sports Medicine › Sports injuries and prevention
- Health Sciences › Medicine › Psychiatry and Mental health › Dementia and Cognitive Impairment Research
- Keywords
- neurodegenerative diseases, rugby union, professional rugby players, Alzheimer's disease, Parkinson's disease, motor neuron disease, dementia, collision sports, long-term health risks, playing position, New Zealand
- MeSH terms
- Adult, Aged, Alzheimer Disease, Football, Humans, Male, Middle Aged, New Zealand, Parkinson Disease, Retrospective Studies, Risk Factors, Proportional Hazards Models, Neurodegenerative Diseases
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