Potent toxin found in brains of dead Alzheimer's victims

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Potent toxin found in brains of dead Alzheimer's victims

Substance made by algae common in lakes, oceans

Margaret Munro

CanWest News Service

April 23, 2005

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 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. 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, " 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.

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 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 , one of the

department's

media relations officers. He says there no plan at this stage to launch

a

followup study.

'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.

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