This is an interesting paper in itself, and its potential implications are even more so. The authors, from the Institute for Ethnomedicine and the University of Miami, have been studying a neurodegenerative condition found among Chamorro villagers on the island of Guam. The disease (Guamanian amyotrophic lateral sclerosis/parkinsonism dementia complex) is characterized by neurofibrillary tangles and beta-amyloid plaques, which puts it right in the middle of a number of other well-known CNS pathologies.
Over the years, it’s been determined that the causative factor is likely beta-N-methylamino-L-alanine (BMAA), which is thoroughly mixed into the local food chain via exposure to cyanobacteria. This new paper details primate studies which show that exposure to this amino acid in the diet is sufficient to bring on the neuropathology, which further strengthens the link. BMAA is apparently substituted for serine in various proteins, to bad effect, and supplemental L-serine has been previously shown to prevent BMAA uptake in cell culture. This new paper also shows that this can prevent the effects seen in the feeding studies.
BMAA-producing cyanobacteria occur globally, perhaps causing similar neuropathologies. Our finding that all of the low-dose vervets developed tauopathies with NFT has implications for human health. BMAA may serve as an environmental trigger for some forms of other neurodegenerative illnesses including sporadic ALS and AD. In human beings, increasing age is a risk factor for ALS, AD and PD. We have initiated experiments to determine if chronic dietary exposures of aged vervets to BMAA results in more profound histopathology.
This reminds me of the work suggesting that exposure to mitochondrial toxins may be a risk factor for Parkinson’s. There’s clearly a lot to learn about these pathways. On one level, it may seem too easy to reach for an environmental cause for these things, but you definitely can’t rule out the idea. Perhaps it’s just a contributory factor in some patients, or it may be something more.