Evidence of chronic traumatic encephalopathy (CTE), a potential cause of dementia caused by repeated blows to the head, has been found in the brains of former association football (soccer) players examined at the University College London Queen Square Brain Bank.
The study, funded by The Drake Foundation and published in the journal Acta Neuropathologica, looked at 14 retired footballers with dementia who were referred to the Old Age Psychiatry Service in Swansea, Wales, between 1980 and 2010. Permission from their next-of-kin was provided to perform post-mortem examinations, which were carried out in six ex-players. Post-mortem analysis of the brain was carried out by researchers from UCL and the National Hospital for Neurology and Neurosurgery.
The team identified CTE pathology in four of the six brains examined, and all six also had signs of Alzheimer’s disease. The rate of CTE identified in the players’ brains exceeds the 12 percent average background rate of CTE found in a previous survey of 268 brains of an unselected population at the Queen Square Brain Bank. Like Alzheimer’s disease, CTE can cause dementia and they are both characterized by a build-up of abnormal tau protein in the brain, but CTE causes tau to accumulate in a distinctive pattern.
Previous studies have found evidence of CTE in the brains of contact sports players, most notably boxers and American football players. Footballers are exposed to repetitive blows to the head from heading the ball and from head-to-player collisions. However, football is unique compared with boxing and American football in that blows to the head are commonly more minor and footballers are less likely to experience significant neurological symptoms or loss of consciousness.
“This is the first time CTE has been confirmed in a group of retired footballers,” explains lead author Dr Helen Ling of the UCL Institute of Neurology, senior research associate at the Department of Molecular Neuroscience and neurologist. “Our findings of CTE in retired [soccer players] suggest a potential link between playing football and the development of degenerative brain pathologies in later life. However, it is important to note that we only studied a small number of retired [players] with dementia and that we still do not know how common dementia is among [players].”
“All of the players whose brain autopsies showed signs of CTE also had Alzheimer’s pathology, but the relationship between the two diseases remains unclear. Both diseases involve a build-up of an insoluble form of tau protein in the brain. However, in CTE tau tends to accumulate around blood vessels and at the depths of the sulci—the grooves in the brain’s surface—which helps to differentiate CTE from Alzheimer’s pathology under the microscope.
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 soccer players would have developed Alzheimer’s disease anyway if they hadn’t played soccer. The most pressing research question is therefore to find out if dementia is more common in soccer players than in the normal population.”