Extensive research from around the world suggests that being a professional footballer carries a higher risk of developing dementia or certain neurodegenerative diseases. One of the most recent studies, carried out in a Spanish population, has been led by researchers from the Clínic-IDIBAPS. Its results indicate that being a professional footballer predisposes to REM sleep disorder and, subsequently, it can evolve towards dementia. The study concludes that, among people with this type of sleep disorder, there is a higher percentage of professional soccer players, compared to the general population.
This work has been coordinated by Dr. Àlex Iranzo, neurologist at Hospital Clínic Barcelona and head of the Clinical Neurophysiology group at IDIBAPS, and has been published in the Journal of Neurology. Patients with REM sleep disorders have vigorous motor behaviors during sleep, nightmares, and lack of muscle relaxation. This disorder especially affects men over 50 years of age.
Previously, Dr. Iranzo and his team had discovered that REM sleep behavior disorder is the first manifestation of some neurodegenerative diseases, such as Parkinson’s disease or Lewy body dementia. In both cases they are entities characterized by the accumulation of alpha-synuclein protein deposits. On the other hand, this sleep disorder is also associated with external risk factors related to the appearance of neurodegenerative diseases, such as head injuries.
Soccer is probably the most popular sport in the world, with more than 38 million federated soccer players who play in practically every country on the planet. As a sport, it has clear benefits for health at a locomotor and cardiorespiratory level, but at the same time it also frequently produces, at a professional level, many injuries to the lower extremities and to the head. A revealing fact indicates that professional footballers have a 50% chance of having a concussion throughout their career, if it exceeds ten years.
The explanation for this phenomenon is, according to Iranzo, that “in contact sports, repeated exposure to blows to the head can induce progressive neuronal loss or the accumulation of alpha-synuclein protein deposits. This is a possible explanation for why in soccer and other contact sports, professional athletes can develop different types of neurodegenerative diseases a few decades after retiring.” In the report published in the Journal of Neurology, the behaviors of patients treated at the Sleep Disorders center of the Neurology Department of the Clínic were analyzed between March 1994 and March 2022. The objective was to find out how many of these patients with REM sleep disorders had been professional footballers.
During the study, 338 people were diagnosed with a REM sleep disorder, of which 228 were Spanish men. Of these, 34% developed a neurodegenerative disease after a follow-up period of seven years. Of the 228 men, six (2.63%) had been professional soccer players and had developed a long career of 13 years on average. Between the time of retirement from football and the diagnosis of REM sleep disorder, nearly 40 years passed.
The study group was compared with a control group also made up of 228 men of the same age, in which it turned out that none had been professional soccer players. The study group was also compared with the general population and it was seen that 0.062% had been professional soccer players. These data show that there was a higher percentage of professional soccer players in the group with REM sleep disorder, compared to the control group and the general population (2.63% vs 0% vs 0.062%). At the time of diagnosis, all the retired soccer players in the study group had disease biomarkers related to alpha-synuclein deposits, and five of them went on to develop Parkinson’s or Lewy body dementia four years after their REM sleep disorder diagnosis and 44 years after they retired.
According to Àlex Iranzo “the association between neurodegenerative diseases and head injuries leads us to speculate that, in the retired soccer players in our study group, repeated exposure to blows to the head may be one of the factors that contributed to the appearance of REM sleep disorder and subsequently to Parkinson’s and dementia”.
The prestigious scientific journal The Lancet has published the conclusions of another study carried out on a group made up of professional and amateur soccer players who had played at least one game in the Swedish first division between 1924 and 2019. In total, 6,007 soccer players were included, of which 510 were goalkeepers. The risk of neurodegenerative disease, such as Alzheimer’s or dementia, was higher among soccer players than among general population controls, and was higher among outfield players than goalkeepers. However, in this study, it was observed that motor neurodegenerative diseases, such as Parkinson’s, were equally or less common in soccer players compared to the general population.
Along the same lines, the results of a study by the University of Glasgow have been identified. Former professional soccer players are more likely to die with a neurodegenerative condition such as dementia or Parkinson’s than the general population, according to this study, which adds that the cumulative impact of heading the ball could be related to brain injuries. The research compared the death records of 7,676 men who played professional football in Scotland between 1900 and 1976 with 23,000 age-selected records from the general population. The report details that, compared to the general population, former soccer players in this study were five times more likely to have Alzheimer’s and twice as likely to have Parkinson’s. On the plus side, soccer players were less likely to die from other common diseases, such as heart disease and some types of cancer, including lung cancer.
It must be borne in mind that most patients with REM sleep disorders are not soccer players, nor do most professional soccer players develop neurodegenerative diseases. Furthermore, due to the variability of results between studies, more studies with more specific designs are still needed to arrive at conclusive results. However, determining whether a retired soccer player has a REM sleep disorder can help identify a population at risk with possible latent neurodegenerative disease.
