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Footballers may be at heightened risk of brain trauma linked to dementia

But crucially it’s not known if Alzheimer’s disease is more common in footballers

Caroline White

Wednesday, 15 February 2017

Footballers may be at heightened risk of a particular type of neurological trauma that has been linked to dementia, suggests a very small study* published in the journal Acta Neuropathologica.

The researchers, from the Queen Square Brain Bank in London, base their findings on 14 retired footballers with dementia, who were referred to the Old Age Psychiatry Service in Swansea between 1980 and 2010.

Evidence of chronic traumatic encephalopathy (CTE) was found in four out of the six whose brains were examined after death. All six also had signs of Alzheimer's disease.

The rate of CTE identified in the footballers' brains is higher than the 12% prevalence of CTE found in a previous survey of 268 brains of an unselected group of people at the Brain Bank.

Like Alzheimer's disease, CTE can cause dementia. Both conditions feature a build-up of abnormal tau protein in the brain, but CTE causes tau to accumulate in a distinctive pattern around blood vessels and in the grooves of the brain’s surface.

Previous research has found evidence of CTE in the brains of contact sports players, most notably boxers and American footballers.

Footballers sustain repetitive blows to the head from heading the ball and from head on collisions with other players. But blows to the head in football are usually more minor, while footballers are less likely to experience significant neurological symptoms or lose consciousness than boxers or American footballers.

"This is the first time CTE has been confirmed in a group of retired footballers," explains lead author Dr Helen Ling, UCL Institute of Neurology. "Our findings…suggest a potential link between playing football and the development of degenerative brain pathologies in later life.”

But she cautioned: “However, it is important to note that we only studied a small number of retired footballers with dementia and that we still do not know how common dementia is among footballers."

The association between CTE and Alzheimer's disease isn’t clear, she said. “Previous studies have shown that the risk of Alzheimer's disease is increased in people with previous head injuries. On the other hand, the risk of dementia is also increased with age and we don't know if these footballers would have developed Alzheimer's disease anyway if they hadn't played football.

“The most pressing research question is therefore to find out if dementia is more common in footballers than in the normal population."

The 14 retired footballers in the study all started playing football and heading the ball in their childhood or early teens and continued to play regularly for an average of 26 years.

Six had been concussed with loss of consciousness while playing football, but this added up to just one episode each during their playing career. The earliest symptoms of dementia started while they were in their 60s and they survived for an average of 10 more years. Twelve out of 14 died of advanced dementia.

"We do not yet know exactly what causes CTE in footballers or how significant the risk is," says co- author Huw Morris, UCL Institute of Neurology. "Major head injuries in football are more commonly caused by player collisions rather than heading the ball. The average footballer heads the ball thousands of times throughout their career, but this seldom causes noticeable neurological symptoms.

“More research is now urgently needed to determine the risks associated with playing football so that any necessary protective measures can be put in place to minimise potential long-term damage."

Of the 14 footballers included in the study, 13 were former professionals and one was a committed amateur who played every season for 23 years.

“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,” commented Dr Elizabeth Coulthard, consultant senior lecturer in dementia neurology, University of Bristol.

She continued: “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.”

And she suggested: “While larger trials are carried out, it seems sensible to take practical measures to minimise the risk of head injury from sport.”

* Ling H, et al. Mixed pathologies including chronic traumatic encephalopathy account for dementia in retired association football (soccer) players. Acta Neuropathol, 2017. DOI: 10.1007/s00401-017-1680-3

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