We tested the brain tissues of the Chamorro people of Guam who died of amyotrophic lateral sclerosis/Parkinsonism dimentia complex (ALS/PDC) for the neurotoxin beta-methylamino-l-alanine (BMAA). We used validated high-pressure liquid chromatography and liquid chromatography-mass spectrometry analyses to test well-characterized archival tissues of the superior frontal gyrus from eight Chamorros from Guam and a comparison group of 15 Canadians. BMAA was found as a free amino acid in 83% of Chamorro ALS/PDC patients (3-10 microg/g) as a protein-associated amino acid in 100% of the Chamorro individuals (149-1190 microg/g). Both forms of BMAA were also found at comparable levels in two Canadians who died of progressive neurodegenerative disease. BMAA, which is produced by cyanobacteria, may be associated with some cases of neurodegenerative disease.

The Chamorro people of Guam have been afflicted with a complex of neurodegenerative diseases (now known as ALS-PDC) with similarities to ALS, AD, and PD at a far higher rate than other populations throughout the world. Chamorro consumption of flying foxes may have generated sufficiently high cumulative doses of plant neurotoxins to result in ALS-PDC neuropathologies, since the flying foxes forage on neurotoxic cycad seeds.

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