My Name’5 Doddie Foundation response to links between rugby and MND

Over the last couple of days, you may have seen articles in the press and on social media claiming that rugby can cause motor neuron disease (MND). My Name’5 Doddie Foundation would like to clarify a few points regarding this.

Much of this coverage, while well-intentioned, may have missed or not made clear, key points regarding existing studies and data, leading to inaccurate headlines and stories which may have caused alarm.

MND research is complex, and this is no exception. Therefore, in typical straight-talking Doddie fashion, we’d like to give you some clarity on the research landscape involving rugby and MND to date, along with what we’re doing to better understand any potential connections.

• There is currently no consensus on whether playing elite level sports increases the risk of MND: there are both positive and negative studies that have been published and many of the studies have used small sample sizes resulting in unreliable results.
• There is no evidence that head trauma causes MND.
• There is some emerging evidence that a specific genetic makeup in a very small subset of people could predispose to MND, if combined with a lifestyle that involves strenuous physical activity. This should not cause alarm, and needs further exploration and validation.
• The benefits of exercising vastly outweigh any potential risk, and exercise is an essential part of a healthy lifestyle.
• My Name’5 Doddie Foundation is committed to continuing to fund studies to further understand any link between MND and sport.

Small studies and unreliable data:

Some published studies have suggested that there’s a correlation between playing elite-level rugby and a higher likelihood of developing MND. Because MND is an uncommon disease, one downfall of these studies to date has been small sample sizes, meaning that the data is not very reliable.

Following the release of a 2022 study linking elite-level Scottish rugby to MND, we issued a statement welcoming the research, but urging caution when drawing conclusions from the data due to the very small number of people with MND in the study. We called for further investigation into this potential link in the form of larger studies.

Correlation doesn’t always mean causation:

These studies have also not provided evidence of causation (i.e. that it’s specifically rugby causing MND). Therefore, if there is a correlation between playing elite-level rugby and developing MND, it could be caused by other factors associated with, but not exclusive to, rugby. We will explore some of these other factors in more detail below:

Head trauma

One suggested link between rugby and MND is the head trauma that some rugby players experience over the course of their career. The connection between head trauma and dementia (particularly chronic traumatic encephalopathy dementia) is well-documented – however MND is a separate disease and currently there is no robust evidence to suggest that head trauma also causes MND.

That said, My Name’5 Doddie Foundation (alongside MND Association and MND Scotland) funded a large-scale study led by Professor Willie Stewart at the University of Glasgow to examine the relationship between traumatic brain injury (TBI) and the risk of developing MND. The research has recently published and showed from using UK-wide electronic health records from over 340,000 adults between 2005 and 2020, that individuals with a history of TBI were over twice as likely to receive a subsequent MND diagnosis compared with matched individuals without a history of TBI. However, it is important to note that this risk was confined to the first two years following the injury; after those two years no long-term risk was observed. As the increased risk was mostly seen during the two years immediately after the injury, it suggests that TBI might be an early sign of MND rather than a cause of the disease. This is because there is the potential for someone who has not yet been diagnosed with MND but is at the earliest stages of the disease to be unsteady on their feet, which may mean they’re more likely to fall and suffer a TBI.

Rugby is not the only elite sport that has been linked to higher rates of MND diagnosis versus that of the general public. Various sports, from football to long distance cross-country skiing have also been linked to MND. While football sees regular head impacts from headers, long distance cross-country skiing is not a sport associated with head trauma, which further suggests a lack of connection between head trauma and MND. As an example, outside of sport, older studies have indicated that military veterans, who are also unlikely to suffer regular head trauma, are also more likely to develop MND than non-veterans.

Strenuous physical activity

A suggested connection between MND and certain elite-level sports is whether strenuous physical activity could be linked to the development of MND in people with a specific gene mutation. In 2022, My Name’5 Doddie Foundation co-funded Professor Dame Pamela Shaw, Dr Johnathan Cooper-Knock, Dr Ryan West and their team at Sheffield Institute for Translational Neuroscience (SITraN) to investigate the link between strenuous physical activity and MND. They recently published their research and spoke to us to discuss their findings.

Early emerging data from the team suggests a small subset of males may have a genetic make-up that could increase their risk of developing MND in combination with a lifestyle that includes strenuous physical activity. However, this is still early data that requires further validation and exploration by the team. It is very important to note that the vast majority of males who performed strenuous levels of activity did not go on to develop MND.

This research highlights the complex way in which genetics and environmental factors could interact in the development of MND. It opens up important avenues of investigation into intense physical exercise and MND. Most people who participate in strenuous physical exercise and most athletes will never go on to develop MND as taking part in exercise alone is not enough to increase the risk of developing the disease.

If you’re interested in hearing more on the subject, in 2022 Professor Kevin Talbot spoke with our patron, Jill Douglas, and Head of Medical Affairs, Sean McGrath, on the topic during an Ask the Expert session on ‘Identifying the Causes of MND’. This link will take you to the stage of the interview where sports and strenuous physical exercise are discussed.

In conclusion

While small-scale existing studies have suggested a correlation between MND and elite-level rugby, the data should be treated with caution as small sample sizes can lead to unreliable results and therefore larger scale studies need to be conducted to investigate the links further.

There is currently no evidence that head trauma causes MND. However, there is emerging data that suggests there could be certain genetic characteristics that, in combination with strenuous physical activity, could predispose for MND in a very small subset of people, but there is no need for alarm. The risk of developing MND depends on a number of things including genetics, ageing and other factors we’re still figuring out. It is important to make clear that most people who participate in strenuous physical exercise and most athletes will never go on to develop MND, as taking part in exercise alone is not enough to increase the risk of developing the disease.

However, we do know that exercise is an essential part of a healthy lifestyle, preventing many health conditions such as cardiovascular disease, dementia and stroke, as well as improving mental and social wellbeing as outlined by the NHS. Therefore, it is important to emphasise that the benefits of exercising vastly outweigh any potential risk.

My Name’5 Doddie Foundation is committed to funding research to unravel any potential links between sport, rugby, exercise and MND and we will always have the MND community at the heart of everything we do. We will continue to share information with our community and make it as understandable, accessible and relevant as possible. Thank you to our supporters for continuing to make this vital research possible, none of this would be possible without your incredible efforts.