Alzheimer’s disease experts have sought to calm fears that toxins found in algae around the UK could be causing dementia.
Researchers in the US recently found evidence which suggested that blue-green alga or cyanobacteria - an organism found in water around the world - can produce a toxin linked to the development of a neurodegenerative disease similar to Alzheimer’s.
The mysterious illness among populations in the Pacific Island of Guam which is similar to Parkinson’s, motor neurone disease and Alzheimer’s prompted researchers to attempt to pinpoint a potential environmental cause.
The team at the Institute for EthnoMedicine in Wyoming reached their conclusion by analysing cyanobacteria that lives in marine, brackish and freshwater environments across the world, CBS News reported.
The study published in ‘Proceedings of the Royal Society B’ journal linked the disease in Guam to a neurotoxin called BMAA. As well as algae, the toxin is present in cycad seeds - which Chamorro villagers on the Pacific island use to make flour tortillas.
Researchers also fed vervet monkeys fruit laced with BMAA, and found that the animals had developed neurofibrillary tangles and plaque which are linked to neurodegenerative diseases.
BMAA was also discovered in 12 freshwater lakes and reservoirs across the UK and in seafood from isolated areas of the Mediterranean, sparking fears that the toxin may cause conditions such as Alzheimer's to develop via the foodchain.
Professor Paul Cox, director of the Institute for Ethnomedicine, told the Mail on Sunday: "We know the single biggest risk factor for Alzheimer’s disease is age, and as our population ages, people will get it more. Secondly, we are getting better at diagnosing and finding Alzheimer’s cases.
"We are adding the possibility of a third factor" adding: "BMAA could be a contributory factor in some people."
However, he stressed that the researchers were not asserting that they had caused Alzheimer’s in the monkeys and that the brain plaques present were different to those believed to cause Alzheimer's.
Dr Doug Brown, Director of Research at Alzheimer’s Society, mirrored Professor Cox’s assurance.
Describing the study as "interesting" he said it shed light on the rare neurodegenerative disease in Guam but "does not provide any evidence that the toxin contributes to Alzheimer’s disease in other populations."
"Feeding the toxin to monkeys caused them to develop the tangles and plaques seen in the brains of people with Alzheimer’s disease, but as the monkeys did not develop any clinical symptoms, we cannot say they would have developed the disease in full."
He went on that while BMAA was identified in mussels and oysters on the Mediterranean coast "there is no evidence that exposure to these sources is linked to an increased risk of Alzheimer’s disease."
"It is not clear whether the link between BMAA and the neurodegenerative disease seen in Guam has any relevance to the majority of cases of dementia worldwide."
Dr Laura Phipps, from Alzheimer’s Research UK, took a similarly cautious view.
"While investigating rare forms of dementia can lead to insights into the more common causes of the condition, further research is needed to understand whether the findings have relevance to diseases like Alzheimer’s or motor neurone disease in other parts of the world."
She went on to stress: "We know that the majority of cases of Alzheimer’s are caused by a mix of age, genetic and lifestyle factors. Currently, the best evidence for reducing dementia risk includes not smoking, keeping blood pressure in check, getting enough exercise and eating a healthy and balanced diet."
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