Is Soccer Playing a Risk Factor for ALS?

To better understand an apparent outbreak of amyotrophic lateral sclerosis (ALS) among professional soccer players in Italy, these authors studied the incidence of ALS among all 7325 Italians who played pro soccer there between 1970 and 2002. They found five ALS cases -- 6.5 times more than the expected number (0.77). This increase was significant during the period 1980 to 2000 and significantly associated, in a dose-response way, with duration of active competition. There was a significant excess of bulbar onset (3 cases).

The investigators considered four possible explanations for this cluster of ALS cases: participation in sports or heavy exercise; trauma specifically related to soccer; use of performance-enhancing drugs; and exposure to …