Mar 22, 2023

Wednesday, 22 March, 2023 Elite male soccer players are 1.5 times more likely to develop neurodegenerative disease compared to population controls, according to an observational study from Sweden’s Karolinska Institutet. In recent years, there have been growing concerns about exposure to head trauma in sport and whether it can lead to increased risk of neurodegenerative disease later in life. A recent study of Scottish international rugby union players found their risk of neurodegenerative disease was more than double that of the general population, while a 2019 study suggested that Scottish soccer players were 3.5 times more likely to develop neurodegenerative disease. This latest study used Sweden’s national health registers to look for records of neurodegenerative disease (diagnoses, deaths or use of prescription drugs for dementia) in 6007 male soccer players who had played in the Swedish top division from 1924 to 2019. It compared players’ risk of neurodegenerative disease with population controls, who were people matched with players according to sex, age and region of residence. The analysis broke down the risk for different neurodegenerative conditions and also compared the risks between outfield players and goalkeepers. The results were published in The Lancet Public Health . Overall, soccer players had a 1.5 times increased risk of neurodegenerative disease compared to controls: 9% (537 out of 6007) of players compared to 6% (3485 out of 56,168) of controls were diagnosed with neurodegenerative disease; the authors noted that, as most participants were still alive at the end of data collection, the lifetime risk of developing neurodegenerative disease for both groups are likely to be higher. The risk of neurodegenerative disease was 1.5 times higher for outfield players compared to controls but was not significantly higher for goalkeepers compared to controls. Accordingly, in a direct comparison, outfield players had a 1.4 times higher risk of neurodegenerative disease compared to goalkeepers. “Our findings suggest that goalkeepers don’t have the same increased risk of neurodegenerative disease as outfield players,” said Assistant Professor Peter Ueda. “Goalkeepers rarely head the ball, unlike outfield players, but are exposed to similar environments and lifestyles during their football careers and perhaps also after retirement. It has been hypothesised that repetitive mild head trauma sustained through heading the ball is the reason football players are at increased risk, and it could be that the difference in neurodegenerative disease risk between these two types of players supports this theory.” Soccer players had a 1.6 times increased risk of Alzheimer’s disease and other dementias compared to controls — with 8% (491 out of 6007) of players being diagnosed with the condition compared to 5% (2889 out of 56,168) of controls. There was no significant risk increase for players versus controls observed for motor neuron disease. The risk of Parkinson’s disease was lower among players and overall mortality was slightly lower compared to the control group (40% versus 42%). “The lower overall mortality we observed among footballers indicates that their overall health was better than the general population, likely because of maintaining good physical fitness from frequently playing football,” said senior researcher Björn Pasternak. “Physical activity is associated with a lower risk of dementia, so it could be hypothesised that the potential risks from head impacts are being somewhat offset by having good physical fitness. Good physical fitness may also be the reason behind the lower risk of Parkinson’s disease.” The authors acknowledged that the findings’ generalisability to soccer-playing today is uncertain, as most players in the study played soccer during the mid-20th century and soccer has changed in many ways since then. It may be that switching from leather to synthetic balls (that do not soak up water and become heavier), having more rigorous training and better equipment, or switching towards a playstyle associated with less head trauma may have reduced the risk. On the other hand, the risk might be higher among players who nowadays train and play more intensely from a young age. The study also looked at male elite soccer players only, so the study’s generalisability to female elite players and to male and female amateur and youth players is uncertain. “As there are growing calls from within the sport for greater measures to protect brain health, our study adds to the limited evidence base and can be used to guide decisions on how to manage these risks,” Ueda concluded. Image credit: iStock.com/decisiveimages