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Scientists publishing in Acta Neuropathologica report that in retired footballers with a past history of repetitive head impacts, chronic traumatic encephalopathy (CTE) is a potential neurodegenerative cause of dementia and motor impairments.
Prof. Roxana Carare, Professor of Clinical Neuroanatomy, University of Southampton, said:
“Although the authors emphasise that their study includes only a small number of cases, they have formulated a reasonable working hypothesis that ‘chronic traumatic encephalopathy in retired footballers are related to their past prolonged exposure to repetitive sub concussive head impacts from heading and head-to-player collisions.’
“Substantiation of this hypothesis will require careful follow-up of a large number of footballers but already there may be enough evidence to examine the pattern of head injuries particularly during games of professional football. Of course funding and increased awareness of this subject of research should follow.
“This obviously has important cultural implications for much of the world but collecting clinical and pathological data could help to make the game safer so that professional footballers can enjoy a long and happy retirement.”
Dr James Pickett, Head of Research, Alzheimer’s Society, said:
“This research broadens an important area of investigation into sports-related head injuries and dementia that has caused much recent speculation. However, these results do not provide proof that heading a football, or sustaining a head injury by any other means during the sport, is linked to developing dementia.
“It is good to see long-term studies that take medical data such as reported concussions into account, but the study lacks important genetic and lifestyle information for the people involved. We know that these factors play a big role in influencing a person’s risk of dementia and so need to be accounted for when understanding how the condition has developed.
“To be able to gather the robust data that we need, studies should include much larger numbers of participants than used here and need to compare footballers who do not have cognitive problems with those who do. These factors will help us to unpick the answers to a complex and under researched issue.
“Exercise is one of the best ways to reduce your risk of dementia and it’s important to ensure that people playing any kind of sport are able to do safely.”
Dr David Reynolds, Chief Scientific Officer, Alzheimer’s Research UK, said:
“Links between head injury and dementia are just beginning to be explored in more detail and this study showing evidence of CTE in a small number of retired football players highlights the need for further research. We can’t tell what ultimately caused these players to develop dementia and this study doesn’t suggest that people who play football are at a greater risk of dementia than the general population.
“While we know that concussion and severe head injury can have a negative effect on brain function, we do not know the consequences of repetitive, low-impact blows to the head, such as those from heading a football. Long-term studies following large groups of people with appropriate controls are needed to better understand any links between playing football and dementia.
“The causes of dementia are complex and it is likely that the condition is caused by a combination of age, lifestyle and genetic factors. Further research is needed to shed light on how lifestyle factors such as playing sport may alter dementia risk, and how this sits in the context of the well-established benefits of being physically active.”
Prof. Rob Howard, Professor of Old Age Psychiatry, UCL, said:
“With the limitations that this is a very small and potentially unrepresentative sample, the demonstration of chronic traumatic encephalopathy in the brains of soccer players is important. We’ve known that the concussive impacts experienced by American Football players can lead to this pathology, but this paper suggests that aspects of ‘real’ football – perhaps repeatedly heading the ball – might also result in serious long term brain damage.
“However, the fact that an association between chronic traumatic encephalopathy and soccer hasn’t previously emerged would suggest to me that it may only be individuals who suffer the most serious repeated minor head trauma who go on to develop these problems. It is premature to be too alarmed about the dangers of routine amounts of heading.”
Dr Elizabeth Coulthard, Consultant Senior Lecturer in Dementia Neurology, University of Bristol, said:
“This is detailed and robust work, albeit in a small number of people. Post mortem work is important as it is often not possible to tell while a patient is alive whether they suffer with chronic traumatic encephalopathy alone, other forms of dementia or a combination of problems.
“There is evidence accumulating that repeated mild head trauma, such as from heading a football, can contribute to brain damage in later life that might cause or exacerbate dementia. However, we have yet to prove this with prospective studies.
“Importantly, we do not know how many minor head injuries might predispose to dementia. Also, we do not yet know at what level of head injury the long term risks of minor head injury outweigh the general health benefits of these sports.
“While larger trials are carried out, it seems sensible to take practical measures to minimise the risk of head injury from sport.”
Dr Sujoy Mukherjee, Workstream Lead for Dementia Strategic Clinical Leadership Group (London), Faculty of Old Age Psychiatry, The Royal College of Psychiatrists and Consultant Psychiatrist, West London Mental Health NHS Trust, said:
“Despite having a relatively small sample, it is an interesting study questioning a possible correlation between association football and CTE (Chronic Traumatic Encephalopathy) progressing to dementia.
“Repeated blows to the head can happen in a number of contact sports and other conditions which can result in CTE (Chronic Traumatic Encephalopathy) and there is a good body of evidence linking it to boxing, American football and many other activities.
“It is important to understand that at present CTE (Chronic Traumatic Encephalopathy) by itself can’t be diagnosed clinically in a living person, though a lot of research is ongoing. It is also unclear what proportion of cases may eventually progress to dementia and its possible relationship with other common causes of dementia like Alzheimer’s disease.
“From a clinical point of view a very important finding in this study is the relative young age of onset of dementia in most of the six cases that had post mortem examination and definitive diagnosis. As dementia is relatively less common in people under the age of 65 years, this may further support the authors’ argument that large case control studies are needed for footballers to identify any possible vulnerable group and to explore possibility of developing protective measures. However, it is by no means aimed to discourage people to participate in this popular sport.”
* ‘Mixed pathologies including chronic traumatic encephalopathy account for dementia in retired association football (soccer) players’ by Ling et al. published in Acta Neuropathologica on Wednesday 15th February.
Declared interests
Prof. Carare: “No conflicts of interest.”
Dr Pickett: “No interests to declare.”
Dr Reynolds: “As a former employee I own shares in Merck Inc and Pfizer.”
Prof. Howard: None received
Dr Coulthard: “I have no conflicts of interest.”
Dr Mukherjee: “I have no conflict of interest to declare.”