according to Italian researchers who reviewed trading cards of about 25,000 male professional soccer players who played in Italy. The researchers then scanned news reports to find which of those players developed the rare neurologic disease. Players who developed ALS were a much younger age at diagnosis when compared with the general population, according to the researchers, who will present their findings at the annual meeting of the American Academy of Neurology.
While the findings might implicate professional-level soccer in the development of ALS, there could be other factors at work, said lead author, of the Mario Negri Institute for Pharmacological Research, Milan. “Repeated traumatic events, heavy physical exercise, and substance use could also be factors in the increased ALS risk among soccer players,” Dr. Beghi said in a news release. “In addition, genetics may play a role.”
The ALS-related deaths of several Italian pro soccer players sparked suggestions that the disease and the sport could be somehow linked, according to Dr. Beghi and colleagues. To determine whether professional soccer players are at increased ALS risk, they reviewed the archives of the country’s major soccer card publisher from the years 1959 to 2000, recording the name, date, and place of birth; field position; and team history for the tens of thousands of players they identified.
News reports revealed that 33 players in that cohort developed ALS, compared with 17.6 cases that would be expected based on Italian general population estimates, according to Dr. Beghi and colleagues.
The number of cases per 100,000 person-years was 1.9 for all the soccer players, and 4.7 for those who were younger than 45 years at diagnosis, researchers said. In general, soccer players were younger at diagnosis, with a median age of ALS onset of 43.3 years, versus 62.5 years in the general population, they added.
These findings cannot be applied to those who play soccer below the professional level, since only professional athletes were studied, Dr. Beghi said. Moreover, the results should not be construed to suggest that people avoid playing soccer, he said, adding that the researchers had few specific details on the players’ ALS diagnoses.
Patients with ALS more often report head injuries, compared with the general population, while links between exercise and ALS have been found in some studies, but not others, according to the researchers.
“Clinical and experimental observations suggest an association between ALS and use of nonsteroidal anti-inflammatory agents and dietary supplements, including branched chain amino acids,” researchers added in the abstract for their report.
The study by Dr. Beghi and colleagues was supported by the Mario Negri Institute in Milan.