Independent report

Motor neurone disease in professional sportspeople: IIAC information note

Published 9 October 2025

Introduction

1. There is considerable public and professional interest in the risk of neurodegenerative diseases associated with participation in a range of professional sporting activities. A number of high-profile individuals have been affected, and recommendations have been made limiting head impacts in a number of sports.

2. The Industrial Injuries Advisory Council (IIAC) has been actively considering the issues in relation to motor neurone disease (MND) and this information note summarises the research the Council has reviewed and its current position on the matter. The condition can be referred to as amotrophic lateral sclerosis (ALS) but IIAC now prefers the term MND.  ALS is the commonest form of MND though there are other rarer variants such as progressive muscular atrophy and primary lateral sclerosis. The terms ALS and MND often appear to be used interchangeably in the literature. The term ALS has been retained in this document where studies specifically refer to that rather than MND.

3. IIAC has commissioned external reviews of the scientific literature relating to dementia and Parkinson’s disease in professional sportspeople from the University of Manchester. Reports on these topics should be available by mid-2026 and IIAC will consider these issues once again at that stage.

Background

4. IIAC last considered the issue of neurodegenerative diseases in professional sportspeople in a 2016 information note (Neurodegenerative diseases in professional sportspersons: IIAC information note). The Council noted that more evidence existed for an increased risk of MND than existed for the other neurodegenerative conditions. However, the evidence at that time was inconsistent and was largely based on a series of overlapping Italian soccer studies. Given the various limitations in the evidence base, the Council was unable to recommend prescription for MND in professional sportspeople at that time.

5. MND is a fatal neurodegenerative disease of largely unknown aetiology that is characterised by rapidly progressive paralysis, leading ultimately to death within three to five years of symptom onset. The annual incidence of MND in England is approximately 2 per 100,000 and is slightly higher in men than in women. It increases rapidly after the age of 40 and reaches a peak at 70 to 74 years (Opie-Martin et al 2021).

Epidemiological studies of MND and sportspeople

6. IIAC identified epidemiological studies relating to MND amongst professional American football players and soccer players. There is a single study of international rugby players that includes elite players that are likely to be both professional and amateur, there are seven potentially overlapping studies relating to other professional sports, and there are a number of potentially relevant studies relating to amateur sport.

Studies of professional American football players

7. There were four studies of MND in professional American football players. They were likely to have largely overlapping study populations, and the Council considered it inappropriate to treat them as providing evidence that was independent of each other and so only the largest and most recent study (Daneshvar et al 2021) was included (Table 1).

8. The three studies excluded from the table were: Abel (2007), which studied National Football League (NFL) players who competed after 1980; Lehman et al (2012), which studied those who played for at least five seasons between 1959 and 1988; and Nguyen (2019), which extended the Lehman et al study to 2013.

9. The Daneshvar et al (2021) study identified 19,423 players who began playing between 1960 and 2019 and played for at least one season using a database compiled by Hidden Game Sports/24-7 Baseball LLC.  Diagnoses of MND and information about death were obtained from NFL statistics aggregators, news reports, obituaries and the National Death Index.  It is noteworthy that only twenty-two of the twenty-eight deaths attributed to ALS were confirmed on the National Death Index. The standardised mortality rate (SMR) was reported to be 3.94 (95%CI: 2.62 - 5.69) and the standardised incidence rate (SIR) 3.59 (95%CI: 2.58 - 4.93).

Studies of professional soccer players

10. There were eleven studies of professional soccer players. Of these, the six Italian studies were likely to have largely overlapping populations, and two from Scotland had identical populations. As above, only the most recent publications from each country were considered.

11. The included studies are listed in Table 2. Two of the five studies reported significantly increased relative risks (Pupillo et al, and Russell et al), while the other three studies had relative risk estimates that were not significantly different from one.

12. Pupillo et al (2020) used the database of an Italian soccer cards publisher to identify 23,586 players active in one of the three top leagues (Series A, B or C) for the period 1959-2000. They identified thirty-four MND cases up to 2018 using internet searches, journalists’ records, and information in two published books. The SIR was 1.91 (95%CI: 1.32 - 2.67).

13. Gamez and Carmona (2021) identified seven MND cases which developed between 2000 and 2020 in former Spanish league soccer players using the records of a specialist unit, internet searches and media reports. The SIR was 2.11 (95%CI: 0.85 - 4.37).

14. Russell et al (2021) identified players from the Scottish Soccer Museum and from individual league clubs’ records. 79% of players could be linked to a Community Health Index allowing details of diagnoses and death certification to be extracted. These were matched to randomly selected general population controls in a 1:3 ratio by sex, year of birth and degree of social deprivation. There were twenty-four MND cases identified amongst the soccer players. The hazard ratio (HR) for a diagnosis of MND in the players compared with the controls was 4.33 (95%CI: 2.05- 9.15).

15. Orhant et al (2022) identified French footballers who played at least one competitive match in the French professional football championship (first and second divisions) between 1968 and 2015.  They used a variety of means to identify players including data from the French Football Federation, the French Professional Football League, football club and fan websites, and forums and newspaper archives. They obtained data on the cause of death from the French National Institute of Health and Medical Research records. The SMR was 1.10 (95%CI: 0.23 - 3.22).

16. Ueda et al. (2023) identified footballers who played at least one game in the Swedish top division between 1924 and 2019 using data obtained from the Swedish Association of Football Historians and Statisticians. Each footballer was matched to ten control subjects identified from a population register based on year of birth, region of residence and vital status at the start of the player’s career. Diagnoses were identified from the national Cause of Death Register and the National Patient Register. The HR for a diagnosis of MND in the players compared with the controls was 1.27 (95%CI: 0.73 -2.22) and the HR for death with MND was HR 1.41 (95%CI: 0.79 - 2.53).

Studies of other professional sportspeople

17. There was limited evidence about the risk of MND in other professional sportspeople and six studies are included in Table 3. Chio et al (2009) did not identify any cases amongst 1,973 professional basketball players and 1,701 professional cyclists. Nguyen et al (2019) reported a lower rate of MND in basketball players compared with American football players (HR 0.35: 95%CI 0.01-1.3). Longstreth et al (1988) found a lower rate of MND in those employed as a professional athlete compared with control subjects (odds ratio (OR) 0.43: 95%CI: 0.04 - 4.56).

18. There were three largely overlapping studies based on the US National Occupational Mortality Survey (Schulte et al 1996, Park et al 2005, Vanacore et al 2010). The largest and most recent of these (Vanacore et al, 2010) reported an increased risk of death due to MND in professional athletes (OR 1.81: 95%CI 0.50–6.77). A European case-control study (Pupillo et al, 2014) also reported an increased risk of death from MND amongst those participating in professional sport (OR 1.41: 95% CI 0.66-2.99).

19.There was a single study of elite rugby players that was likely to include some professionals. Russell et al (2022) identified 654 former Scottish international rugby players aged thirty years or more in December 2020 from a published book and a rugby website. 412 (63%) of the players could be linked to a Community Health Index number. Each player was matched to three general population control subjects based on year of birth and socioeconomic status. Outcomes were determined from the Scottish Morbidity Record and death certificates. There were no MND cases amongst the control subjects and one subject was arbitrarily assigned a MND diagnosis to allow a HR (15.2: 95%CI 2.1-179) to be calculated.

20. There were a number of studies of amateur sports and other forms of physical activity that were also excluded. These showed a wide range of risks and the Council considered them to be less relevant to the issues relating to professional sporting activities, amateurs having lower levels of physical fitness in general and are likely to have less impactful head collisions when they occur.

Conclusions

21. A wide range of risks is reported in studies examining the relationship between professional sporting activity and MND.  Many of the papers have potential limitations in relation to the identification of relevant study populations, the identification of those with MND, the reliability of diagnoses, and the selection of appropriate reference populations, and linkage of the study population to disease registers and death certification.

22. The mechanism underlying a possible association between sporting activity and MND is unclear. There are studies showing an association between physical activity and MND, and Mendelian randomisation studies suggesting an association between genetic susceptibilities to both (Julian et al, 2021). The epidemiological evidence in professional sportspeople relates primarily to American football and soccer, both of which are associated with head impacts.

23. There is evidence of an association between MND and head injury (Watanabe and Watanabe 2017) but no clear direct mechanistic pathway between the two, particularly in the case of repeated sub-concussive head impacts, which are likely to occur in a number of contact sports.

24. For IIAC to recommend prescription based on epidemiological evidence the exposure-related risk in a particular group of paid employees should be at least twice that of non-exposed individuals. The recommendation should also be unlikely to be overturned by future research.

25. IIAC takes the view that the current evidence base, while stronger than the last time Council reviewed this information, is not sufficiently clear nor consistent enough to allow prescription for MND in professional sportspeople.

26. IIAC is aware that further studies are underway or are planned and are likely to provide additional information about the relationship between professional sport and MND.  Also, the commissioned reviews of cognitive impairment and Parkinson’s disease might provide additional relevant information. IIAC will revisit the topic when sufficient further information becomes available.

References

Abel, E.L., 2007. Football increases the risk for Lou Gehrig’s disease, amyotrophic lateral sclerosis. Percept. Mot. Skills 104 (June (3 Pt 2)), 1251–1254.

Chio, A., Calvo, A., Dossena, M., Ghiglione, P., Mutani, R., & Mora, G. (2009). ALS in Italian professional soccer players: the risk is still present and could be soccer-specific. Amyotroph Lateral Scler, 10(4), 205-209.

Daneshvar, D. H., Mez, J., Alosco, M. L. et al. (2021). Incidence of and Mortality From Amyotrophic Lateral Sclerosis in National Football League Athletes. JAMA Netw Open, 4(12), e2138801.

Julian TH, Glascow N, Barry ADF, Moll T, Harvey C, Klimentidis YC, et al. Physical exercise is a risk factor for amyotrophic lateral sclerosis: convergent evidence from Mendelian randomisation, transcriptomics and risk genotypes. EBioMedicine  2021;68:103397.

Gamez, J., & Carmona, F. (2021). Confirmation of early non-bulbar onset of amyotrophic lateral sclerosis in Spanish league soccer players. J Neurol Sci, 428, 117586.

Lehman, E. J., Hein, M. J., Baron, S. L., & Gersic, C. M. (2012). Neurodegenerative causes of death among retired National Football League players. Neurology, 79(19), 1970-1974.

Longstreth, W. T., McGuire, V., Koepsell, T. D., Wang, Y., & van Belle, G. (1998). Risk of amyotrophic lateral sclerosis and history of physical activity: a population-based case-control study. Arch Neurol, 55(2), 201-206.

Nguyen, V. T., Zafonte, R. D., Chen, J. T. et al  (2019). Mortality Among Professional American-Style Football Players and Professional American Baseball Players. JAMA Netw Open, 2(5), e194223.

Opie-Martin S, Ossher L, Bredin A et al. Motor Neuron Disease Register for England, Wales and Northern Ireland-an analysis of incidence in England. Amyotroph Lateral Scler Frontotemporal Degener. 2021 Feb;22(1-2):86-93.

Orhant, E., Carling, C., Chapellier, J. F., Marchand, J. L., Pradat, P. F., Elbaz, A., Maniez, S., Moisan, F., & Rochcongar, P. (2022). A retrospective analysis of all-cause and cause-specific mortality rates in French male professional footballers. Scand J Med Sci Sports, 32(9), 1389-1399.

Park RM, Schulte PA, Bowman JD, Walker JT, Bondy SC, Yost MG, Touchstone JA, Dosemeci M. Potential occupational risks for neurodegenerative diseases. Am J Ind Med. 2005 Jul;48(1):63-77.

Pupillo, E., Bianchi, E., Vanacore, N et al (2020). Increased risk and early onset of ALS in professional players from Italian Soccer Teams. Amyotroph Lateral Scler Frontotemporal Degener, 21(5-6), 403-409.

Pupillo, E., Messina, P., Giussani, G, et al (2014). Physical activity and amyotrophic lateral sclerosis: a European population-based case-control study. Ann Neurol, 75(5), 708-716.

Russell, E. R., Mackay, D. F., Stewart, K., MacLean, J. A., Pell, J. P., & Stewart, W. (2021). Association of Field Position and Career Length With Risk of Neurodegenerative Disease in Male Former Professional Soccer Players. JAMA Neurol, 78(9), 1057-1063.

Russell, E. R., Mackay, D. F., Lyall, D., Stewart, K., MacLean, J. A., Robson, J., Pell, J. P., & Stewart, W. (2022). Neurodegenerative disease risk among former international rugby union players. Journal of Neurology, Neurosurgery & Psychiatry, 93(12), 1262-1268.

Ueda, P., Pasternak, B., Lim, C.-E., Neovius, M., Kader, M., Forssblad, M., Ludvigsson, J. F., & Svanström, H. (2023). Neurodegenerative disease among male elite football (soccer) players in Sweden: a cohort study. The Lancet Public Health, 8(4), e256-e265.

Vanacore, N., Cocco, P., Fadda, D., & Dosemeci, M. (2010). Job strain, hypoxia and risk of amyotrophic lateral sclerosis: Results from a death certificate study. Amyotroph Lateral Scler, 11(5), 430-434.

Watanabe Y, Watanabe T. Meta-analytic evaluation of the association between head injury and risk of amyotrophic lateral sclerosis. Eur J Epidemiol. 2017 Oct;32(10):867-879.

Tables

Comparison of measures of risk used in the tables

Measure	Definition	Typical use
Relative Risk (RR)	Probability of event in exposed ÷ probability in unexposed	Cohort studies, clinical trials
Odds Ratio (OR)	Odds of event in exposed ÷ odds in exposed	Case-control studies
Hazard Ratio (HR)	Instantaneous event rate in exposed ÷ rate in unexposed	Survival analysis (e.g. Cox model)
Standardised Incidence Ratio (SIR)	Observed cases ÷ expected cases (adjusted for demographics)	Occupational / environmental exposure studies
Standardised Mortality Ration (SMR)	Observed deaths ÷ expected deaths (adjusted for demographics)	Mortality studies in exposed cohorts

Table 1: study of professional American footballers

Reference	Study Type, numbers	Exposure Assessment	Identification of cases	Measure of risk (95%CI)	Additional information
Daneshvar (2021)	Mortality survey 19,423 players 38 ALS diagnoses	National Football League debuted 1960-2019 played at least 1 season	NFL statistics aggregators, news reports, obituaries, and the National Death Index	SMR 3.94 (2.62 - 5.69) based on US mortality rates SIR 3.59 (2.58 - 4.93) based on Californian rates	Reliability of diagnoses is uncertain. Only 22 of 28 deaths were confirmed to have ALS with 2 attributed to other causes and 4 unknown. It is not clear if the SMR relates to all deaths or the 22 confirmed cases

Table 2: studies of professional soccer players

Reference	Study Type, numbers	Exposure Assessment	Identification of cases	Measure of risk (95%CI)	Additional information
Pupillo (2020)	Cohort study 23,586 players 34 ALS diagnoses	Italy Series A, B, C played 1959-2000 identified from records of an Italian soccer cards publisher	Internet searches, published books, journalists’ records	SIR 1.91 (1.32 - 2.67) based on North Italian rates	Reliability of diagnoses is uncertain rates fell with age and were higher in 1st and 2nd division players than 3rd
Gamez (2021)	Cohort study 7 ALS diagnoses	Former Spanish league players	Specialist ALS unit records, internet searches, and media reports diagnosed 2000-2020	SIR 2.11 (0.85 - 4.37)	Reliability of diagnoses is uncertain 3 cases in semi-professionals source of reference data for SIR calculation is unclear
Russell (2021)	Cohort study 7676 former players 24 MND diagnoses matched to population controls in 1:3 ratio	Archives of the Scottish Soccer Museum and individual league club records. professional players born before 1976	Community Health Index (CHI) 23 cases identified in control population	HR 4.33 (2.05- 9.15)	Relatively low proportion of footballers linked to the CHI. Evidence of poor reliability of MND diagnoses on CHI
Orhant (2022)	Cohort study 5,639 players 3 ALS deaths	Played ≥ 1 match in French 1st and 2nd divisions 1968-2015	Football clubs and associations, fan websites and forums, newspaper archives	SMR 1.10 (0.23 - 3.22)	Reliability of diagnoses is uncertain
Ueda (2023)	Cohort study 6229 players 14 ALS cases matched to population controls in 1:10 ratio	Swedish Association of Football Historians and Statisticians.  Played ≥ 1 game in Swedish top division 1924-2019	National Cause of Death Register and the National Patient Register 100 cases and 84 deaths amongst control population.	HR 1.27 (0.73 -2.22) for diagnosis HR 1.41 (0.79 - 2.53) for death

Table 3: studies of other professional sportspeople

Reference	Study Type, numbers	Exposure Assessment	Identification of cases	Measure of risk (95%CI)	Additional information
Chio  (2009)	Cohort study 1973 players 0 ALS cases	Italian major league basketball players 1980-2004 at least 1 season	Death certificates, ALS centre archives, Italian ALS Assn, media and websites, self-reports.	n/a	none
Chio  (2009)	Cohort study  1701 cyclists 0 ALS deaths	Historical Yearbook of Italian Professional Cyclists 1945-2001 at least 1 race	Death certificates, ALS centre archives, Italian ALS Assn media and websites, self-reports.	n/a	none
Nguyen (2019)	Cohort mortality study 2708 baseball players 3 ALS deaths	Lahman Baseball Database born 1915-1965 played ≥ 5 seasons played after 1958	National Death Index	HR 0.35 (0.01 - 1.3)	HR relative to NFL players
Longstreth (1998)	Case-control 174 ALS patients 348 control subjects	Ever employed as a professional athlete	Diagnosis by a local neurologist controls: telephone dialling and Medicare eligibility lists	OR 0.43 (0.04 - 4.56)	Association reported with participation in organised sports during high school OR 1.52 (1.03-2.25)
Vanacore (2010)	Case control 14,628 ALS deaths 58,512 controls	US National Occupational Mortality Surveillance System.  24 states 1984-1998	US National Occupational Mortality Surveillance System 24 US states 1984-1998	OR 1.81 (0.50–6.77)	6 ‘professional athletes’ amongst ALS deaths; 13 in control subjects
Pupillo (2014)	Case-control 625 ALS patients 1,166 controls	Structured questionnaire	European ALS registry controls from GP registers	OR 1.41 (0.66-2.99)	15 ‘professional sports activity’ in ALS patients, 17 in control subjects
Russell (2022)	412 international rugby players matched to population controls in 1:3 ratio	Published book and rugby website	CHI.  5 cases in ex-players, 0 in control population.	HR 15.2 (2.1-179)	1 control subject assigned a MND diagnosis to calculate the HR.  Likely to include amateur players.