Toxin Found In Brains Of
Dead Alzheimer's Victims
Substance Made By Algae Common In Lakes, Oceans

By Margaret Munro
CanWest News Service
A potent toxin produced by common algae has been found in the brains of nine Canadians who died of Alzheimer's disease.
The same neurotoxin has turned up in brain tissues taken from people in Guam who died of dementia, say researchers, who warn that chronic exposure to the algal toxins may pose a public health threat.
It "may now be prudent" to monitor drinking water and food for the toxin known as BMAA, short for beta-n-methylamino-L-alanine, an international team reports in the Proceedings of the National Academic of Sciences this month.
BMAA is produced by cyanobacteria, ubiquitous algae common to lakes, oceans and the soil, and can build up in the food chain.
A Canadian dementia specialist stresses the evidence linking the toxin to Alzheimer's disease is circumstantial. But he says it is "intriguing" and warrants followup.
"It's a red flag, an alert, that we've got to look into," says Dr. Jack Diamond, scientific director of the Alzheimer Society of Canada.
He stresses that many risk factors are linked to the mind-destroying disease, and more study is needed to prove BMAA is one of them.
The international team, headed by Paul Cox of the Institute for Ethnomedicine in Hawaii, reports "BMAA was recently discovered in the brain tissues of nine Canadian Alzheimer's patients." The toxin was not detected in 14 other Canadians who died of causes unrelated to neurodegeneration.
Dr. Patrick McGeer at the University of B.C. is reported to have supplied the Canadian brain samples. McGeer is travelling and could not be reach for comment.
"Cyanobacteria might be the ultimate source of the BMAA in the Canadian Alzheimer's patients," Cox and his colleagues suggest in their paper. The team has shown that BMAA is produced by many species of cyanobacteria around the world.
It has long been known cyanobacteria pose health hazards. Drinking water heavily contaminated with the organisms has led to hospitalizations and in some cases death.
Cox and his colleagues believe the BMAA produced by the algae may also act as a "slow toxin." They chemical can be bound by proteins, and gradually released over many years.
They have shown BMAA, from soil-dwelling cyanobacteria, concentrate in plants and flying bats in Guam. The bats are a traditional delicacy of the indigenous Chamorro people, who suffer a high rate of a dementia-related disorders. BMAA has been found in the brains of affected individuals, leading Cox to suggest "Chamorros may unwittingly ingest high levels of BMAA in their traditional diet."
BMAA's chemical signature in the brains of Canadian Alzheimer's patients indicates the problem may not be unique to Guam.
Diamond says the sample size of nine Alzheimer's patients is far too small and a well-controlled study looking at elderly people with and without Alzheimer's is needed to establish a link. "It's an epidemiology study that's needed at this stage," he says. "A big one."
Health Canada scientists are aware of the report and are tracking the scientific literature, says Christopher Williams, one of the department's media relations officers. He says there no plan at this stage to launch a followup study.
Cox's team argues the possible health consequences of chronic exposure to low levels of BMAA deserve more attention.
"It may now be prudent to monitor BMAA concentrations in drinking waters contaminated by cyanobacterial blooms," they say. They also advise checking for BMAA in fish and animals that may be ingesting the microbes.
© The Vancouver Sun 2005



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