(CN) – The risk of developing serious brain diseases among athletes of sports other than football could be more significant than previously expected, after new research shows signs of such issues in the brains of six deceased soccer players.
In findings published Tuesday in the journal Acta Neuropathologica, researchers at University College London present the results of post-mortem tests on the players’ brains – which revealed that four of the six brains examined had chronic traumatic encephalopathy, or CTE. All of the brains had signs of Alzheimer’s disease.
While the study population is small, the findings highlight the risks posed by repeated blows to the head in sports and athletic leagues other than the National Football League, which has received criticism over what critics consider the league’s insufficient response to evidence of former players developing – and sometimes dying from – severe brain diseases.
The rate of CTE identified in the subjects’ brains far exceeds the 12 percent average found in a previous survey of 268 brains of an unselected population at University College London’s Queen Square Brain Bank.
“This is the first time CTE has been confirmed in a group of retired footballers,” explains lead author Helen Ling, senior research associated at the university’s department of molecular neuroscience. “Our findings of CTE in retired footballers suggest a potential link between playing football and the development of degenerative brain pathologies in later life.”
She added, “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 subjects began “heading” soccer balls – striking a ball with his or her head – during their childhood or early teens. The players continued to play soccer regularly for an average of 26 years.
Though each of the brains with CTE also had signs of Alzheimer’s, the team cautions that the relationship between the two diseases remains unclear.
“Previous studies have shown that the risk of Alzheimer’s disease is increased in people with previous head injuries,” Ling said. “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.”
Ling said the most important research question now is whether dementia is more common in soccer players than the general population.
As opposed to the common theory that these diseases stem from repeatedly heading the ball, co-lead author Huw Morris attributes head injuries in soccer to situations in which players crash into each other.
“Major head injuries in football (soccer) are more commonly caused by player collisions rather than heading the ball,” Morris said. “The average footballer heads the ball thousands of times throughout their career, but this seldom causes noticeable neurological symptoms.”
The soccer players were monitored regularly by Don Williams, a psychiatrist in Swansea, England, who collected demographic and clinical data, as well as playing and concussion history from the subjects’ close relatives.
Williams began studying cases of brain diseases connected to sports after he was approached by the son of former soccer player, who asked about the possible cause of his father’s brain issues.
“In 1980, the son of a man with advanced dementia asked me if his father’s condition had been caused by heading the ball for many years,” Williams said. “As a result, I looked out for men with dementia and a significant history of playing soccer, followed them up and where possible arranged for post-mortem studies to be carried out.
“The results suggest that heading the ball over many years, a form of repetitive sub-concussive head injury, can result in the development of CTE and dementia.”