European rugby plays its responsibility in the blood of former players

Fifty-six former rugby players. Blood tests. And significantly elevated tau protein levels in those who sustained more than five concussions during their careers. The UK Rugby Health study published in July 2024 is not the first to document the neurological sequelae of professional rugby, but it is the first from the UK Rugby Health project to explore blood biomarkers in retired rugby players — though its authors cannot yet claim clinical precision, lacking clinically accepted biomarkers at this stage. This shift, from subjective questionnaire to objective biomarker, nonetheless changes the nature of the conversation.

For twenty years, the standard concussion management protocol rested on the Maddocks Score and its five questions asked on the sideline: who is playing whom, what is the score, which half are we in. A player who answered correctly could return. A player who answered correctly but whose brain was slowly bleeding did not know it. Neither did the federations.

Biomarkers do not yet allow diagnosis of chronic traumatic encephalopathy (CTE) in living patients. But they allow dating, quantifying, and comparing levels of injury. For European rugby federations, this is precisely where things become complicated.

The Essential Points

  • The UK Rugby Health study (July 2024) on 56 former professional players shows significantly elevated serum tau and tau-p181 exosome levels in players who suffered more than five declared concussions during their careers. A separate study (ABHC programme, Imperial College London, Brain, 2025) explored similar biomarkers but with different methodology.
  • The Irish clinical trial NCT04485494 measured biomarker use at three precise temporal windows: Day+3, Day+6, Day+13 after a traumatic episode.
  • Collective legal proceedings by former players diagnosed with early-onset neurodegenerative diseases target World Rugby, the RFU (England), the WRU (Wales) and the RFL. A separate proceeding was also launched in France, but its exact defendants have not been confirmed.
  • The shift to biomarkers makes damage measurable retrospectively, which structurally changes the position of federations in legal disputes.
  • The stakes extend beyond sport: they concern the insurability of professional contact and the obligations of sports employers toward their employees.

Twenty Years of Insufficient Protocols Leave a Trace in the Blood

Professional rugby long managed concussions as a short-term performance problem. A dazed player was rested for a few days, re-evaluated by the club’s medical team, then returned to play. The available tools permitted this: normal scan, acceptable questionnaire, return authorized. What the scans did not show was the accumulation of repeated micro-trauma that, over a decade, reaches a clinical threshold.

The tau protein is a marker of neuronal integrity. Normally confined within nerve cells, it appears in the blood when those cells are damaged. Its phosphorylated form, tau-p181, is specifically associated with degeneration processes characteristic of Alzheimer’s disease and CTE. The UK Rugby Health study measured both forms, serum and those encapsulated in exosomes, in 56 former professionals whose careers span the 1980s through 2010s.

The central finding: players who reported more than five concussions present significantly higher levels than players who reported fewer concussions, and significantly higher than controls with no history of traumatic brain injury. The correlation does not prove causality in the legal sense, but it documents it in the epidemiological sense.

What the Irish trial NCT04485494 adds to this is the kinetics. By measuring biomarkers at Day+3, Day+6, and Day+13 after trauma, researchers established that the window of biological recovery does not correspond to the window of symptom recovery. A player may feel recovered at Day+7 while tau levels remain elevated at Day+13. This misalignment lies at the heart of the problem: current protocols track symptoms, not biology.

What Federations Knew, and When They Knew It

The central legal question is not whether concussions damage brains. The scientific literature on this point has been sufficiently convergent since the late 2000s to no longer be debatable. The question is what federations and clubs did with this information, and at what pace they adapted their protocols.

In Great Britain, more than 1,100 former players have sued World Rugby, the Rugby Football Union (RFU), the Welsh Rugby Union (WRU), and the Rugby Football League (RFL). Plaintiffs, several of whom have been diagnosed with CTE, early-onset dementia, or Parkinson’s disease in their forties or fifties, argue that the federations were aware of neurological risks linked to repeated concussions and did not adapt their return-to-play rules in timely fashion.

The proceeding is complex and lengthy, and the federations contest individual causality. But the arrival of biomarkers alters the balance of available evidence. Until now, causality rested primarily on post-mortem autopsies revealing characteristic tau protein deposits in the brains of deceased former players, as shown by the diagnosis of former English international Steve Thompson, who, while still living, was diagnosed with dementia at age 42. Tomorrow, it will rest on blood tests conducted while the patient is living, with a history of declared concussions and dated biomarker levels.

For federations, this is a paradigm shift in evidentiary standards. For lawyers specializing in sports employment law, it is an unprecedented opportunity.

The Irish Trial Opens the Path to an International Clinical Standard

The NCT04485494 trial, conducted in Ireland, helped validate the use of biomarker protocols adapted to the professional rugby calendar. Its merit is as practical as it is scientific: it demonstrates that samples collected within existing sports medical infrastructure produce interpretable data.

The three temporal windows selected correspond to actual professional rugby return-to-play deadlines. Day+3 is the first standard post-traumatic re-evaluation. Day+6 is when most current protocols allow resumption of light training. Day+13 is the upper limit of World Rugby’s standard gradual return-to-play protocol. By measuring biomarkers at these three precise moments, the trial shows that biology and administrative timeline do not systematically coincide.

The scope of this validation extends beyond rugby. The International Football Federation, the NFL medical committee, and the World Anti-Doping Agency follow this research. Association football, a minor contact sport compared to rugby but played by a billion people, is equally concerned: repetition of headers and small trauma without declared clinical concussion has received growing attention since the FIELD study published in the New England Journal of Medicine in 2019, which showed that former professional football players die of neurodegenerative diseases three times more frequently than the general population.

An international clinical biomarker standard, should it emerge in coming years, would very likely rest on protocols validated by trials like NCT04485494. The ability of these biomarkers to objectify return-to-play would transform the medical status of the athlete, already in flux in other dimensions as shown by the analysis of the athlete’s body as a digital asset.

The Responsibility of the Sports Employer Under Common Law

European professional athletes are employees. In France, England, Ireland, Italy, this legal reality produces direct consequences: the employer has a duty of safety toward the employee. This obligation applies to the risk of repeated traumatic brain injury just as it would apply to exposure to toxic substances in a factory.

The comparison is not merely rhetorical. Asbestos litigation established a structuring precedent in France: the employer’s inexcusable fault is recognized as soon as the employer knew of the risk and did not take available protective measures. Lawyers for former French players, preparing proceedings analogous to those brought in Great Britain, work precisely on this ground. The question is not whether rugby is dangerous, but whether clubs did what they knew they could do, from the moment they knew how to do it.

Biomarkers strengthen this argument in two ways. First, they make it possible to establish a link between the intensity of exposure to risk (number of declared concussions, number of seasons played in the top division) and the level of measurable biological injury. Second, they make it possible to date the appearance of warning markers: if a player showed elevated levels at age 35 and his club had regular medical monitoring, the question of what protective measures that monitoring produced becomes legally relevant.

France is not ahead on this issue. The national collective agreement for professional rugby regulates player medical monitoring, but the National Rugby League’s concussion management protocols remain aligned with World Rugby’s minimum recommendations, going no further. Several former Top 14 players, including internationals, have publicly stated they suffer from neurological sequelae and are considering legal action.

Insurers Draw the Line That Federations Failed to Hold

The most immediate economic stakes are not judicial. They are insurance-related. Companies covering European professional clubs are beginning to ask precise questions about concussion management protocols. The arrival of biomarkers as a potential tool for assessing damage changes the actuarial calculation: if one can measure retrospectively the level of neurological injury in a player at the end of his career, the claim becomes quantifiable, which makes it insurable but also billable.

Several major sports insurers have begun including in their contracts clauses conditioning coverage on adoption of defined medical protocols. In other words, a club that does not respect a return-to-play protocol based on documented medical monitoring could face an exclusion clause in the event of neurological claims. This market mechanism pushes clubs in a direction that regulatory provisions were insufficient to impose.

This shift of risk to insurers is not neutral for the economic structure of European professional rugby. Top 14, Premiership, and URC club budgets are already under pressure. A rise in insurance premiums linked to neurological risk, or a restriction of available coverage, would have a direct impact on business models. It would also create financial incentive to select players based on preexisting neurological risk profile, which would open other ethical and legal questions about hiring discrimination.

What the Next Ten Years Will Tell

Biomarkers for repeated traumatic brain injury are not yet standardized clinical diagnostic tools. Their validation in larger cohorts remains necessary. The predictive value of serum tau for identifying players most at risk of developing CTE remains uncertain: the UK Rugby Health study concerns 56 subjects, which is sufficient to establish a statistically significant correlation but insufficient to establish operational clinical thresholds. The authors themselves underscore the absence of clinically accepted biomarkers and call for deepened research before any clinical use.

What these next ten years will tell depends on two variables. The first is scientific: the size of study cohorts. Consortiums like PREVENT Dementia in the United Kingdom or the BU CTE Center in the United States work with cohorts of several thousand patients, athletes and non-athletes. If their results converge with those of UK Rugby Health, the level of evidence will suffice to establish clinical thresholds.

The second variable is institutional. World Rugby announced in 2023 a plan to reform its concussion management protocols, including a commitment to evaluate integration of biomarkers into player medical monitoring. Moreover, the ABHC programme (Imperial College London), funded by the RFU and Premiership Rugby, conducts research on similar biomarkers — an approach that is not inconsequential: institutions that fund research on their own practices expose themselves to its conclusions, but they also have the capacity to translate them into operational protocols faster than those that ignore it. The UK Rugby Health study, meanwhile, was conducted without declared external funding.

Rugby is not the only sport undergoing this transformation. It is simply the first in Europe to see the three dimensions converge simultaneously: science producing objective tools, law seeking quantifiable proof, and the insurance market taking position before federations do. The question that remains open is whether European professional sports institutions will choose to pilot this transition or to endure it.

Sources

  1. Norah Alanazi et al. (senior author: Prof. Paul Chazot, Durham University), “Concussion-Related Biomarker Variations in Retired Rugby Players and Implications for Neurodegenerative Disease Risk: The UK Rugby Health Study”, International Journal of Molecular Sciences, vol. 25, no. 14 (2024): https://www.mdpi.com/1422-0067/25/14/7811
  2. Clinical Trial NCT04485494, “Blood Biomarkers in Sports-Related Concussion”, ClinicalTrials.gov: https://clinicaltrials.gov/ct2/show/NCT04485494
  3. Mackay et al., “Neurodegenerative Disease Mortality among Former Professional Soccer Players”, New England Journal of Medicine (2019), FIELD study: source identified, institutional URL not verified
  4. World Rugby, “Concussion Management — Graduated Return to Play Protocols”: https://www.world.rugby/the-game/player-welfare/health/concussion/management
  5. Collective proceeding of former British players against World Rugby, RFU, WRU and RFL, reported by The Guardian and BBC Sport (2020-2024): press sources, URLs not verified
  6. UK Rugby Health Study (primary source): https://pmc.ncbi.nlm.nih.gov/articles/PMC11276902/
  7. FIELD Study — NEJM 2019 (footballers): https://pubmed.ncbi.nlm.nih.gov/31633894/
  8. NCT04485494 Protocol (Irish rugby biomarker trial): https://pmc.ncbi.nlm.nih.gov/articles/PMC8323462/
  9. Wikipedia — Steve Thompson: https://en.wikipedia.org/wiki/Steve_Thompson_(rugby_union)
  10. France24/AFP — Rugby Legal Proceedings (December 2025): https://www.france24.com/en/live-news/20251222-rugby-players-lose-order-challenge-in-brain-injury-claim
  11. EurekAlert / Durham University — UK Rugby Health Study Press Release: https://www.eurekalert.org/news-releases/1051389
  12. PMC / CTE Biomarkers Review 2024: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11485022/