This is a MedPage Today story.
Men who played elite soccer were more likely to develop neurodegenerative diseases -- notably, dementia -- as they aged, a study in Sweden showed.
The risk of neurodegenerative disease was 46% higher among soccer players who played in the Swedish top division than in the general population, according to Dr. Peter Ueda of the Karolinska Institute in Stockholm and co-authors.
Alzheimer's disease and dementia were 62% more common among soccer players than controls, the researchers reported in Lancet Public Health.
Goalkeepers did not have an increased risk of neurodegenerative disease but outfield players did, suggesting repetitive hits from heading the ball may be a factor.
"In contrast to outfield players, goalkeepers rarely head the ball," Ueda told MedPage Today. "Although other factors that differ by [soccer] player position could also affect this difference, the finding lends support to the hypothesis that heading the ball may increase the risk of dementia."
A previous study in Scotland showed that neurodegenerative disease mortality among former professional soccer players was about 3.5 times higher than the general population.
More recently, the Scotland research team reported that neurodegenerative disease risk in former soccer players was associated with field position and career length, indicating a higher risk with cumulative exposure to outfield positions.
"The fact that this well-conducted study replicates prior research on [soccer] players in Scotland should convince skeptics that the connection between heading and dementia is real and preventable," said Chris Nowinski of the Concussion Legacy Foundation in Boston, who wasn't involved with the study.
"We need to take steps to minimize risk by increasing the age at which children begin heading, and then take steps to reduce the frequency and magnitude of headers," Nowinski told MedPage Today.
"The Football Association in England is leading the conversation on age of first exposure by eliminating heading before age 12," Nowinski pointed out.
"Other countries should match that policy, and I anticipate the age will increase as people begin to realize the benefits of fewer concussions in children and CTE (chronic traumatic encephalopathy) cases in [soccer] players," he added. "Once heading is introduced, sports organizations need to set strict limits, especially on higher magnitude impacts."
Ueda's research team studied health records of 6,007 male soccer players who played in the Swedish top division Allsvenskan from 1924 through 2019, comparing them with 56,168 matched controls from the general Swedish population.
Over an average follow-up time of 28 years, 8.9% of elite soccer athletes and 6.2% of controls were diagnosed with neurodegenerative disease. A total of 8.2% of soccer players developed Alzheimer's disease or dementia, compared with 5.1% of men in the general population.
The risk of motor neuron disease, including amyotrophic lateral sclerosis (ALS), was similar among players and non-players. Parkinson's disease was less common among soccer players than the general population, and death from any cause was slightly lower.
The lower overall mortality could indicate that elite soccer players have better overall health and physical fitness than the general population, said study co-author Dr. Bjrn Pasternak, also of the Karolinska Institute.
"Physical activity is associated with a lower risk of dementia, so it could be hypothesized that the potential risks from head impacts are being somewhat offset by having good physical fitness," Pasternak said. "Good physical fitness may also be the reason behind the lower risk of Parkinson's disease."
The research shows an association between dementia and elite soccer, not cause-and-effect, Ueda emphasized.
"Even if we would have perfect data on causality, what to do with it is a matter of values and a decision for the broader community and individual players to make," he said. "Our study provides data that could support such decision-making."
"I think it is important to emphasize that these findings are based on elite players who were active mostly during the mid-20th century," Ueda added. "Their applicability to contemporary elite players and to amateur and youth players is uncertain."