Abstract
BackgroundDietary exposure to the cyanotoxin BMAA is suspected to be the cause of amyotrophic lateral sclerosis in the Western Pacific Islands. In Europe and North America, this toxin has been identified in the marine environment of amyotrophic lateral sclerosis clusters but, to date, only few dietary exposures have been described.ObjectivesWe aimed at identifying cluster(s) of amyotrophic lateral sclerosis in the Hérault district, a coastal district from Southern France, and to search, in the identified area(s), for the existence of a potential dietary source of BMAA.MethodsA spatio-temporal cluster analysis was performed in the district, considering all incident amyotrophic lateral sclerosis cases identified from 1994 to 2009 by our expert center. We investigated the cluster area with serial collections of oysters and mussels that were subsequently analyzed blind for BMAA concentrations.ResultsWe found one significant amyotrophic lateral sclerosis cluster (p = 0.0024), surrounding the Thau lagoon, the most important area of shellfish production and consumption along the French Mediterranean coast. BMAA was identified in mussels (1.8 µg/g to 6.0 µg/g) and oysters (0.6 µg/g to 1.6 µg/g). The highest concentrations of BMAA were measured during summer when the highest picocyanobacteria abundances were recorded. ConclusionsWhile it is not possible to ascertain a direct link between shellfish consumption and the existence of this ALS cluster, these results add new data to the potential association of BMAA with sporadic amyotrophic lateral sclerosis, one of the most severe neurodegenerative disorder.
Highlights
Amyotrophic lateral sclerosis (ALS) is one of the most severe neurological disorders with a median time of 36 months between onset and death [1]
As it has already been described that BMAA may be present in marine areas, we aimed to determine whether the littoral location of cluster 1 could account for the existence of the focus
Our study is the first to analyse BMAA in mussel specimens collected almost 20 years ago. These analyses suggest that detection of significant amounts of BMAA in bivalves held in the Thau lagoon is not a novel phenomenon, as marine picocyanobacteria blooms are commom
Summary
Amyotrophic lateral sclerosis (ALS) is one of the most severe neurological disorders with a median time of 36 months between onset and death [1]. In Europe and North America, the dietary source, if any, remains in dispute but Field et al recently reported significant concentrations of BMAA, in crabs similar to those consumed by individuals in a putative ALS cluster in Chesapeake Bay, USA [17]. Such ALS clusters are useful tools for studying potential environmental exposures and the Guam cluster is probably the most investigated one in the world. Conclusions: While it is not possible to ascertain a direct link between shellfish consumption and the existence of this ALS cluster, these results add new data to the potential association of BMAA with sporadic amyotrophic lateral sclerosis, one of the most severe neurodegenerative disorder
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