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A study published in JAMA Neurology looks at Association of Field Position and Career Length With Risk of Neurodegenerative Disease in Male Former Professional Soccer Players
This Roundup accompanied an SMC Briefing.
Prof Peter Passmore, Professor of Ageing and Geriatric Medicine, Queen’s University Belfast, said:
“This is an interesting study which adds to the literature on neurodengenerative disease associations and soccer players. This is a large study, case control design so the numbers involved do indicate strengths in the research.
“The results are qualified in the study limitations described. These are associations and not definitive proven risk factors. The actual risk factors for the varied neurodegenerative conditions have not been studied in enough depth as the confounders are many.
“The references are specifically to CTE but there is little mention in the discussion about major head injuries – for example in goalkeepers – one thinks of Bert Trautmann and other goalkeepers in the 1950’s who often suffered major trauma and were concussed. More recent examples were Hugo Lloris and Peter Cech.
“More definitive studies are needed as the authors suggest.
“Of note not all head trauma is related to heading the ball – many of the more significant repetitive injuries are head to head and elbow to head (the latter is frowned upon and is a sending off offence) this only applies to professional soccer players and those born before 1969.”
Dr Susan Kohlhaas, Director of Research, Alzheimer’s Research UK, said:
“This well-conducted study of dementia risk in ex-professional footballers is another piece of a large and largely unfinished jigsaw when it comes to understanding dementia risk.
“Dementia risk is complex, caused by an interweaving mixture of age, genetics and lifestyle. This is interesting and useful insight into the difference in risk based on player positions and career length and could help inform future research or player management. However, there is still more to do in order to fully understand what is causing increased dementia risk in outfield players. This study did not look at all aspect of players’ lives on or off the pitch to determine what may be behind the increased risk.
“Existing results from this research team have shown that former professional footballers may also get several health benefits of playing the game and therefore it’s important to understand both the benefits and risks of playing professional sport as it relates to dementia.
“Football is close to the hearts of so many of us, and it’s right that authorities and footballing bodies take sensible steps to mitigate the risk of injury to ensure players can enjoy the game safely at all levels. It is good news that further guidance on heading will be introduced into the English game from next season, with all professional, amateur and grassroots clubs involved.
“As the UK’s leading dementia research charity, Alzheimer’s Research UK is committed to improving the understanding of the risk factors associated with dementia. The charity contributed to the Department of Media, Culture and Sports review into head injuries in sport, and our Chief Medical Officer sits on the advisory of the FA’s independent medical advisory board.
“But with nearly one million people in the UK living with dementia, and a huge unmet clinical need, we need to see life-changing news treatments. We will continue to call on footballing bodies, player associations, and governments across to help fund dementia research now, not later, when it is too late.
“Life-changing research is the way to help find a cure.”
Dr Christopher Morris, Senior Lecturer in Neurotoxicology, Newcastle University, said:
“This is a well thought out study looking specifically at a large cohort of former professional football players in Scotland. The study has significant advantages over other studies since it looks at a very long time period, in lots of footballers, and also uses several sources of information to come to the main conclusion. Although the study found a clear increased risk of neurodegeneration, because this is a retrospective study, it’s difficult to identify a cause. The findings do however fit with what we know about repeated head trauma in that it can lead to long term brain damage, and in some cases like the “punch drunk syndrome” seen in former boxers or chronic traumatic encephalopathy in American football players, this can lead to dementia and neurodegeneration.
“The findings support what has been found in several studies, that professional level involvement in several sports where some form of head injury might occur is associated with a range of neurodegenerative disorders, particularly dementia, but also Parkinson’s and motor neurone disease.
“The study does have to be kept in perspective though, since most research shows that physical activity itself and sport in general doesn’t cause neurodegeneration. Instead, it only seems to be certain sports that are linked to disorders like dementia. This is good to know, as sport and physical activity has clear benefits for both physical and mental health. This study was also done in professional players and other similar studies show that sports like football at an amateur level doesn’t appear to link to poor brain health in later life. Although there is a clear increased risk in professional footballers, over 90% of the players in this study didn’t develop a neurodegenerative disorder.
“This research, which only looks at professional footballers, doesn’t provide a reason why there is an increased risk of neurodegeneration. There are some suggestions from this study that the reason might be due to heading the ball as goalkeepers who are less likely to head a football had slightly lower risk. This link to heading a ball, although plausible, isn’t proven and more research will be needed.
“What is unusual in this study is that several different neurodegenerative disorders including dementia, motor neurone disease, and Parkinson’s are linked to professional footballers. Normally these different disorders are quite distinct, both in terms of symptoms, but also in the biology that leads to these conditions. What might be happening here is that head trauma, in this case very small bumps but many of them, and over a very long period, promotes brain damage in general, leaving a person more susceptible to developing a disorder like Alzheimer’s.
“As this is an epidemiological study, what we don’t know is if the disorders being reported in these footballers are definitely what has been suggested, such as Alzheimer’s. This is because we can’t currently give an absolute diagnosis of the specific type of dementia unless we investigate the brain after a person dies. This is how we look for the specific signs in the brain of Parkinson’s, or a dementia such as dementia with Lewy bodies. We know that in American football the changes in the brain that cause neurodegeneration are due to chronic traumatic encephalopathy. What we don’t know with this study is if the dementia, motor neurone disease and Parkinson’s found in footballers also shows signs in the brain of chronic traumatic encephalopathy. That will be one of the next questions to answer, to find out why professional footballers have a greater risk of developing these devastating disorders.”
Prof John Hardy, Professor of Neuroscience, UCL, said:
“This is an important paper which further implicates professional football playing as a risk factor for neurodegenerative disease. Perhaps this is not surprising given the work showing this is true of other contact sports and the previous work showing chronic traumatic encephalopathy in retired players. Recent data from rugby players has shown white matter lesions in active players and one might suppose that similar findings may also be seen in football players. There are many important and practical questions now to be dealt with. Can these sports and the training for them be modified to reduce these problems? What is the mechanism by which these sports influence dementia and what exactly is the pathology? What is the relationship between the acute changes seen in active players with the changes in elderly ex-players in their 60s plus? How relevant are these findings in professional sports players to the playing of sports by the general public?
These are important discussions: but it would be tragic if this type of study led us to become even more a nation of couch potatoes.”
Prof David Curtis, Honorary Professor, UCL Genetics Institute, said:
“This important study provides robust evidence that a career as a professional footballer substantially increases the risk of long term brain damage. The effect size is large. Risk increases by a factor of three or more, meaning that roughly speaking 30% of professional footballers will eventually develop dementia compared with a background rate of 10% in the general population. It seems reasonable to assume that the brain damage occurs as a result of heading the ball and that most heading would occur during training rather than while playing.
“It is extremely difficult to know how this problem should be addressed. Football organisations in England have recently agreed to place limits on heading during training but presumably this will mean that English players will be disadvantaged in terms of their heading skills so it is hard to see that this measure on its own can be a long term solution.”
Prof David Sharp, Centre Director at the UK Dementia Research Institute’s Care Research & Technology Centre based at Imperial College London and the University of Surrey, said:
“These new findings add to the growing evidence linking professional football and the development of dementia later in life. We can see that players who are likely to have had the most head impacts, i.e. as a defender or with longer playing careers, show a striking increase in dementia risk compared to players with lower exposure such as goalkeepers.
“The research suggests that we should be introducing preventative measures to reduce this overall risk of dementia and protect our players. At the same time, we need to address the lack of treatments available for neurodegenerative disease. Dementia is the leading cause of death in England and Wales, and we must do more to understand the underlying biology of these diseases so we can develop treatments.”
‘Association of Field Position and Career Length With Risk of Neurodegenerative Disease in Male Former Professional Soccer Players’ by Emma R. Russel’ by et al. was published in JAMA Neurology at 16:00 UK time on Monday 2 August.
Declared interests
Dr Christopher Morris: “Funded by the Lewy Body Society, Alzheimer’s Society, Alzheimer’s Research UK, National Institutes of Health Research, and Chair of Peer Review Panel for Parkinson’s UK and Multiple Sclerosis Society of Great Britain Brain Bank at Imperial College London.”
Prof John Hardy: “None relevant to this.”
Prof David Curtis: “I have no conflict of interest.”
Prof Dave Sharp: “sits on the Rugby Football Union Concussion Advisory Panel.”
None others received