March 16, 2023

expert reaction to study of elite football players and risk of dementia

A study published in The Lancet Public Health looks at neurodegenerative disease among male elite football players in Sweden.

Prof Huw Williams, Professor of Clinical Neuropsychology, University of Exeter, said:

“This is a remarkable study, comparing cohorts of football players in Sweden across many decades to a sample of the total population of the country (10 controls per player). As such, it is a very strong study form a retrospective longitudinal perspective. Ie looking back from “now” on occurrence of disease over many decades.

“We’ve seen much speculation over whether there is an increased risk of dementia and other neurodegenerative conditions in football /soccer players, particularly as it is hypothesised that there may be impacts on the brain from heading the ball, or blows form head to head clashes or other contacts causing concussion. The increased risk identified in this study was 1.4 times higher in the players, which is lower than suggested by previous studies.  Anything that increases risk of major forms of dementia is important to understand and manage.  Importantly, the risk appears to be limited to those playing before 1970.

“The study doesn’t tell us much about why there may be this increased risk. It may be that these players were more exposed to injuries in play. Goalies appeared less at risk, which is odd, as they may often be in collisions involving head contact. More fine-grained analyses are needed, such as neuroimaging studies. to tell us more about what may lie beneath the headline. Importantly, soccer authorities are paying more attention to the issues, such as concussions, so one hopes better systems for managing wellbeing of players will be developed, so we can have more insights into why there might be a risk for dementia, and what we might do to lessen the risk.

“On a positive note, players seemed to be living longer, with less likelihood of issues such as lung cancer. Therefore, there may be effects of soccer that are protective of health.”

Dr Virginia Newcombe, NIHR Advanced Fellow and Associate Professor, University of Cambridge, said:

“This well-conducted study adds to the growing body of evidence that repetitive head impacts in the sporting arena may lead to an increased risk of neurodegenerative disease. Players in the Swedish top division from 1924 to 2019 were found to have a higher risk of neurodegenerative diseases than controls including Alzheimer’s disease and other dementias. The increased risk in non-goal keeper positions replicates a previous study of former professional soccer players based in Scotland adding weight to the findings. The finding of a lower risk of Parkinson’s Disease contrasts with previous football studies, and is an important avenue for future research to understand why. It will also be important to continue to follow this cohort of players to see if the overall higher risk of neurodegenerative diseases is maintained in those who have played most recently.  

“Further research is urgently needed to identify which players (and why) are at highest risk of neurogenerative disease, to understand how best to diagnose and treat mild head injury and concussions, understand any sex differences to risk, and to follow players in retirement to ensure those who develop problems receive the care they need. Improved knowledge of how best to mitigate the risks will enable playing sport to be enjoyed safely by all.”  

Dr Sara Imarisio, Head of Research at Alzheimer’s Research UK, said:

“This well-conducted study adds to the evidence that former professional footballers face an increased risk of dementia. The research – involving exclusively male, elite players from Sweden – found that former outfield footballers were 1.5 times more likely to develop diseases like Alzheimer’s than non-players of the same age and background. A similar study of former Scottish football players in 2019 identified an even higher 3.5-fold increase.

“The study also found that goalkeepers were not at an increased risk, suggesting that there may be things about outfield play, rather than the lifestyle or background of footballers in general, that causes this link. But there is still more to do to fully understand exactly what’s driving this increased risk, and while heading the ball could be a contributing factor, it’s still possible that other aspects of players’ lives, on or off the pitch, may be a factor too.

“It’s important to note that these findings are specifically from professional male footballers, rather than amateur or casual play. Further research is needed to find out more – including research on female footballers to know whether there could be an increased dementia risk in the women’s game.

“Football is close to the hearts of many of us, and provides opportunities for physical exercise, social engagement and fun. The researchers found that ex-players had a lower risk of other health conditions, and it’s important to acknowledge the huge benefits of playing sports.

“As the UK’s leading dementia research charity, Alzheimer’s Research UK is committed to understanding the risk factors associated with dementia. We’re partnering with public funding bodies to develop a new multi-million-pound national brain injury research platform that will deepen our understanding this field, including how best to identify and care for people with brain injuries.

“Evidence suggests that there are things we can all do to support our brain health. Someone’s risk of dementia is determined by a whole range of things – some we can control, like our lifestyle – and others that we can’t, such as our age, our genes and the environment we live in. So while there’s no sure-fire way to prevent dementia, regular physical, mental and social activity as well as a balanced diet, not smoking, only drinking in moderation, and maintaining a healthy weight and blood pressure have all been linked with a healthy brain. People can find out more about supporting their brain health by taking our Think Brain Health Check-in at www.alzheimersresearchuk.org/brain-health/check-in/

“Anyone concerned about changes in their memory and thinking skills, or who thinks they might be showing signs of dementia, should speak to their GP.”

Dr Keith Parry, Head of Department, Department of Sport and Event Management, Bournemouth University, said:

“This article is based on a cohort study that features a large number of cases over an extended period of time. The findings from this study add to a growing body of evidence that there is a link between playing football and an increased risk of certain neurodegenerative diseases. When combined with the finding last year that there is a causal link between repetitive head impacts and Chronic Traumatic Encephalopathy (another neurodegenerative disease), this study should act as a further wake-up call for football governing bodies. With growing evidence around the risks from aspects of the game, all governing bodies of football should question whether it is safe for children in particular to head the ball and consider removing heading from practices at the very least.

Although the data provided here points to the general health benefits from playing football, this study indicates that more needs to be done in football and other sports to keep players safe from brain injuries. Players should be made aware of the fact that they are at greater risk of developing Alzheimer’s disease and other dementias.”

Christopher Nowinski et al. Applying the Bradford Hill Criteria for Causation to Repetitive Head Impacts and Chronic Traumatic Encephalopathy, Frontiers in Neurology, https://doi.org/10.3389/fneur.2022.938163

Dr Llwyd Orton, Senior Lecturer in Neurophysiology, Manchester Metropolitan University, said:

While the paper and press release do reflect the evidence, the title of the press release is not appropriate. The main conclusions of the study are drawn from historical data, with the main conclusions being interpreted from footballers who played their first match in the Swedish top division in 1959 or earlier. The classification used for inclusion in the footballer group was that players played at least one game in the Allsvenskan, which is not a fair comparison to modern elite footballers. The phrasing “are more likely” in the press release title implies that the findings of this study can be translated to modern elite players when this is debateable at best. Any wider reporting of this study in the press should ensure that the findings are placed in an appropriate historical context. There is a risk with the title of the press release that the message conveyed could be alarmist to the general population and not reflective of the evidence.

Prof Gill Livingston, Professor in Psychiatry of older people, UCL, said:

“This is a high-quality paper and findings are in line with a previous large study of French professional footballers which found a similar excess risk of dementia but a decreased mortality rate from other illnesses and a Scottish study which found an even higher excess risk. Again, the finding is that the risk is from football positions which are likely to have more head contact or injury from the ball. Other studies have found that longer time playing football increases risk. This is convincing evidence. It is important to keep in mind that people playing football live longer than people they are compared with. People fear developing dementia – these findings point to ways we can reduce it and not only for footballers. We need to act to protect people’s heads and brains and keep playing sport.”

Bruno D, Rutherford A. Cognitive ability in former professional football (soccer) players is associated with estimated heading frequency. J Neuropsychol 2022;16(2):434-43. doi: 10.1111/jnp.12264

Russell ER, Mackay DF, Stewart K, et al. Association of Field Position and Career Length With Risk of Neurodegenerative Disease in Male Former Professional Soccer Players. Jama Neurology 2021;78(9):1057-63. doi: 10.1001/jamaneurol.2021.2403

Prof Sir John Hardy, Chair of the Molecular Biology of Neurological Disease, University College London (UCL), said:

“This study adds to the now convincing data that contact sports lead to increased dementia risk.  It is worth noting that, strictly, one cannot be sure that the association is with confirmed Alzheimer’s disease and not with dementia overall.  This distinction may be important as we try and understand disease mechanisms. The study does make clear that this association should be of concern to the ruling bodies of football and other contact sports even if we are not yet quite clear what element of the game is causing the problem, be it heading or head clashing.

Dr Chris Morris, Senior Lecturer, Newcastle Brain Tissue Resource, Newcastle University, said:

“The current Swedish study adds to the growing evidence that playing football at a professional level can increase the risk of developing memory impairment and dementia. Like the UK based study, the outcomes are broadly similar, with an increased risk for players on the field but not for goalkeepers. This might imply that heading the heavier ball used in the past could be a factor that contributes to dementia.”

“One thing that is different in the Swedish study is that the risk of developing other brain disorders such as Parkinson’s or motor neurone disease doesn’t seem to be increased. In the case of Parkinson’s, this is actually decreased and that is unusual. Why the two studies have slightly different findings is unclear, and larger and more extensive studies will be needed to identify why these differences occur. It does suggest though, that changes caused by repeated small head impacts over a very long time does lead to damage in the parts of the brain involved with memory and can increase the chances of someone developing dementia.“

“It has to be stressed here that the study doesn’t show that playing football at an amateur level is bad for brain health. Many large studies show that physical activity such as football is good for both long term general health and for mental health. The risks found in this Swedish study only apply to footballers playing at the very highest levels of the game, and the risk is still relatively small.”

Prof Tara Spires-Jones, Professor of Neurodegeneration and deputy director of the Centre for Discovery Brain Sciences at the University of Edinburgh, and BNA President-Elect, said:

“In this robust study, Ueda and colleagues examined medical records from more than 6000 football players and more than 55,000 people who did not play elite football. The scientists found that playing football was associated with higher risk of Alzheimer’s and other dementias. Their finding that goalkeepers – who do not “head” the ball often did not have increased risk while outfield players did have increased dementia risk adds to the large amount of scientific evidence that head injury increases risk of dementias.  While this paper and others indicates that elite sports where head impacts occur increase risk of dementias, it is also worth noting that there is a large body of evidence that exercise in the general population decreases dementia risk.  My take home message from all of the available data including this paper is protect your brain by both exercising and avoiding head injury/impacts.”

Prof David Curtis, Honorary Professor, UCL Genetics Institute, said:

“This study replicates previous findings that playing professional football is associated with substantially increased risk of dementia. It seems extremely plausible that repeatedly heading the ball during training and normal play produces brain damage which over time can result in dementia. The fact that the risk to goalkeepers, who rarely head the ball, is not increased strengthens this hypothesis. The effect is large – this study estimates that the risk of dementia increases about one and a half times. If we assume that about one in ten people would develop dementia anyway then this means that about one in twenty professional footballers will develop dementia who would not otherwise have done so, as a result of heading the ball.”

‘Neurodegenerative disease among male elite football (soccer) players in Sweden: a cohort study’ by Peter Ueda et al. was published in The Lancet Public Health at 23:30 UK time on Thursday 16^th March.

DOI: https://doi.org/10.1016/S2468-2667(23)00027-0

Declared interests

Dr Virginia Newcombe: “No declarations of interest.”

Dr Chris Morris: “Funding from Alzheimer’s Research UK and Medical Research Council.”

Prof Gill Livingston: “I have no interests to declare.”

Prof Sir John Hardy: “No conflicts.”

Prof Tara Spires-Jones: “No conflicts.”

Prof David Curtis: “No conflicts.” 

For all other experts, no reply to our request for DOIs was received.