People who play football professionally are not only at higher risk of suffering Motor Neuron Disease (MND), but also develop the symptoms far earlier than the general population, a new study suggests. While there has been plenty of recent research showing the neurological consequences of a career in America's National Football League, this is about those who play what the rest of the world calls football, but Americans (and Australians) refer to as soccer. Once again, however, blows to the head appear the most likely explanation.
After some Italian professional footballers died of MND, also known as Amyotrophic lateral sclerosis (ALS), people wondered if this was just a random coincidence or examples of a wider problem. Dr Ettore Beghi of the Mario Negri institute for Pharmacological Research turned to the archive of a publisher of football trading cards, and found records of 25,000 players from Italy's male professional league between 1959 and 2000.
The cards include not only who the players played for and their position, but the more medically useful date of birth. Beghi and colleagues searched news reports to find out what happened to the players after they retired. In 33 cases this involved the development of ALS.
Since news reports, particularly in regard to less famous players, are likely to be far less comprehensive than medical records, the true number is probably considerably higher. Yet even with 33 diagnoses, this is 3.2 cases of ALS per 100,000 people per year. Among the Italian population in general the rate is 1.7.
That gap is suspicious, but the really dramatic difference was for early onset. Despite famous cases like Stephen Hawking and Lou Gehrig (MND/ALS is also known as Lou Gehrig's disease), diagnosed in their 20s and 30s respectively, the average age of MND onset is 63. Among the football players, however, Beghi will report to the American Academy of Neurology's annual meeting in May, the average was 43 and diagnosis before 45 was 4.7 times more common than for the wider Italian population.
"It is important to note that repeated traumatic events, heavy physical exercise and substance use could also be factors in the increased ALS risk among soccer players," Beghi said in a statement. "In addition, genetics may play a role."
A little over one person in a thousand developing MND, some of whom would have got it anyway, is unlikely to be enough to deter many young athletes dreaming of professional careers, or change the rules of a global obsession. Beghi and colleagues also note the work's relevance to people who play less frequently is unclear. Given the health benefits of regular exercise, Beghi isn't advocating people stop playing soccer.
However, the findings may lead to better information about the causes of ALS, and needs to be combined with evidence frequent heading of soccer balls can lead to brain injuries and dementia.
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