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Algae toxin linked
to Alzheimer's
By Margaret Munro
CanWest News Service
Taken from the Victoria
Times Colonist, April 23rd, 2005
Researchers find
same chemical in brains of victims in Canada, Guam
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 neural 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-methyl-lamino-L-alaninie, and 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
followsup. "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 Canadian who died of causes unrelated to neurodegenerations.
Dr. Patrick McGeer
at the University of British Columbia is reported to have supplied the
Canadian brain samples. McGeer is traveling and could not be reached 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 hospitalization and in some cases death.
Cox and his colleagues
believe the BMAA produced by the algae may also act as a "slow toxin."
The 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-controled
study looking at elderly people with and without Alzheimer's is needed
to establish a link. "It's an epidemioloty 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 is 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 water contaminated
by cyanobacterial blooms," they say. They also advise checking for
BMAA in fish and animals that may be ingesting the microbes.
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