Higher risk of dementia in Swedish top-division football players
Men who played football (soccer) in the Swedish top division until the mid 1900s had a higher risk of dementia than men from the general population, a new study from Karolinska Institutet published in The Lancet Public Health reports.
“The higher risk of dementia was only seen in outfield players, not goalkeepers, supporting the hypothesis that heading the ball and head collisions on the field could increase the risk of dementia,” says principal investigator Peter Ueda, assistant professor at the Department of Medicine, Solna, Karolinska Institutet. “But it’s also possible that the observed link is attributable to other factors specific to football players. We also cannot draw any conclusions about the risk faced by today’s male and female elite players, nor by amateur and youth players.”
There have been concerns that contact sports in which the player is exposed to head impacts could, potentially, cause brain damage. Heading of the ball in football has also been identified as a possible risk factor. In 2021, the English Football Association decided to recommend a limit to the number of headers performed by players during training. The recommendation came after the publication of a Scottish study that showed a three- to five-fold increased risk of neurodegenerative diseases such as dementia, ALS and Parkinson’s disease in former professional players.
Now, researchers at Karolinska Institutet have studied the risk for dementia and other neurodegenerative diseases among elite footballers in Sweden relative to that of the general population.
Studied over 6,000 players
The researchers studied over 6,000 footballers active in the top division (Allsvenskan) between 1924 and 2019, and compared their health registry data with a control group comprising over 56,000 men of the same region of residence and age as the football players.
The study showed that footballers had a 62 percent elevated risk of dementia compared with the control group. On the other hand, the risk for Parkinson’s disease was 32 percent lower. ALS was too rare for the analyses to provide any reliable results. The study also showed that the footballers lived slightly longer on average than other men.
“Our results were not as alarming as those of the Scottish study,” says Peter Ueda. “We don’t know why the results of the two studies are partly different and would need more detailed data on headers and head collisions to study if there are possible causal relationships, and if so, how large they are. Dementia is a common disease with a lifetime risk of 10 to 20 percent. Put very simply, our results indicate that the lifetime risk of a top-division footballer active in Sweden up to the middle of the last century is around 15 to 30 percent.”
Possible protective factors as well
The researchers note that exposures related to football could both increase and decrease risk of neurodegenerative disease. For example, an association between physical activity levels and a lower risk of dementia and Parkinson’s disease has been observed in other studies.
“It could be that the risks of dementia are being somewhat offset by the footballers’ higher levels of physical activity. Good physical fitness may also be the reason behind the lower risk of Parkinson’s disease,” says co-author Björn Pasternak, senior researcher at the Department of Medicine, Solna, Karolinska Institutet.
The researchers note that many of the players in the study were relatively young or still active, meaning that they had not reached the age when neurodegenerative diseases typically develop. Since playing styles, practice routines and equipment have changed in the past century the risks for contemporary elite players might differ from that of football players who were active up until the mid-20th century. By way of example, Peter Ueda points out that the leather balls that were used until the latter half of the 20th century have been replaced by synthetic balls that do not soak up water.
The study was financed by the Folksam Research Foundation, the Swedish Research Council for Sports Science, the Hedberg Foundation, Neurofonden, the Åhlén Foundation and Karolinska Institutet.
Publication
“Neurodegenerative disease among male elite football (soccer) players in Sweden: a cohort study.” Peter Ueda, Björn Pasternak, Carl-Emil Lim, Martin Neovius, Manzur Kader, Magnus Forssblad, Jonas F Ludvigsson, Henrik Svanström, The Lancet Public Health, online March 16, 2023, doi: 10.1016/S2468-2667(23)00027-0