Confirmation of early non-bulbar onset of amyotrophic lateral sclerosis in Spanish league soccer players

Abstract

Objective: Sports-related activity has been proposed as a risk factor for ALS, particularly among professionals playing American football and soccer, with a reported prevalence between two and forty times higher than the general population. Early onset (by two decades) was described among Italian soccer players as early as 2005. This study aims to characterise the phenotype of seven Spanish retired professional and semi-professional soccer players.

Methods: The cases were identified using the following sources: (i) personal archives from a leading ALS Unit, (ii) PubMed and specialised websites, and (iii) self-reports of patients in the media. Age and site of onset, survival time, history of trauma, playing position and time between retirement and first symptoms were investigated for soccer players in the Spanish league diagnosed between 2000 and 2020.

Results: Seven ALS cases were identified. The mean age at onset was 41.5 years (SD 9.2, median 45.5, range 31.5-51.2). Onset was bulbar in one individual, while six experienced spinal onset. Three patients had the flail arm syndrome variant. Two cases were goalkeepers, two defenders and three midfielders. Four had a history of trauma (two serious). Survival time for the two deceased patients was 71.8 months. Mean time between retirement and first symptoms was 9.4 years (SD 8.0, median 15.2, range 0.1-17.5).

Conclusions: Our study has the largest sample size of non-Italian league soccer professionals and semi-professionals, and our results corroborate early onset (by 23.7 years). Unlike the Italian cohorts, bulbar onset is rare, and upper limb onset is most common.

Keywords: Amyotrophic lateral sclerosis; Early onset; Physical exercise; Risk factor; Soccer; Trauma.