Does Blue-Green Algae Cause Motor Neuron Disease?

Does blue-green algae cause Motor Neuron Disease?

Does blue-green algae cause Motor Neuron Disease?

Check out this answer from Consensus:

Blue-green algae produce a variety of toxins that can have severe neurotoxic effects. While there is evidence that these toxins can cause significant brain damage, more research is needed to establish a direct link between blue-green algae exposure and Motor Neuron Disease. Given the potential health risks, it is crucial to continue monitoring and regulating water sources to prevent exposure to these harmful toxins.


Blue-green algae, also known as cyanobacteria, are a group of photosynthetic bacteria found in various aquatic environments. These microorganisms are known for their ability to produce a range of toxins that can pose significant health risks to humans and animals. This article explores the potential link between blue-green algae and Motor Neuron Disease (MND), a progressive neurological disorder that affects motor neurons in the brain and spinal cord.

Blue-Green Algae and Their Toxins

Blue-green algae produce several types of toxins, including hepatotoxic peptides, cytotoxic alkaloids, neurotoxic alkaloids, and saxitoxin derivatives. These toxins can contaminate drinking water and recreational water sources, leading to various health issues. For instance, exposure to water containing toxic blue-green algae has been associated with illnesses ranging from acute pneumonia and hepatoenteritis to mild skin irritation and gastroenteritis1.

Neurotoxic Effects of Blue-Green Algae

One of the neurotoxic compounds produced by blue-green algae is Anatoxin-a. This toxin has been shown to have significant histopathological effects on the brain. In a study involving male laboratory mice, exposure to Anatoxin-a resulted in the decay of gray matter, shrinkage of neurons, and other severe brain damage3. These findings suggest that neurotoxic compounds from blue-green algae can have detrimental effects on the nervous system.

Mechanisms of Neuronal Damage

The mechanisms by which blue-green algae toxins cause neuronal damage are complex. For example, Anatoxin-a can lead to the hyperpolarization of neuronal membranes, reducing neuronal firing and modulating synaptic transmission2. This disruption in neuronal activity can contribute to the degeneration of motor neurons, potentially linking blue-green algae exposure to conditions like MND.

Evidence Linking Blue-Green Algae to MND

While there is substantial evidence that blue-green algae produce neurotoxic compounds capable of causing significant brain damage, direct evidence linking these toxins to MND in humans is still limited. However, the histopathological effects observed in animal studies provide a basis for further investigation into this potential link3.


Does blue-green algae cause Motor Neuron Disease?

Rachael Dunlop has answered Near Certain

An expert from Macquarie University in Neuroscience, Cell Biology, Molecular Biology, Neurobiology

A link between blue green algae (BGA) and motor neurone disease (MND) was first suspected when researchers began investigating an unusual neurodegenerative disease amongst the indigenous people of the tiny South Pacific island of Guam. Almost half of the adult population presented with a combination of diseases including MND, Parkinson’s and Alzheimer’s disease, yet a painstaking search for a genetic cause turned up nothing. Researchers then focused on the Islander’s diet for clues – one of their staple foods was flour made from the seeds of cycads, a tree that had a symbiotic relationship with the BGA that grew in its roots where it fixed nitrogen for the tree. The villagers also ate fruit bats, which fed on the cycad seeds. Analysis of the seeds, the bats, and the flour revealed a new toxin – known as BMAA – that was eventually linked back to the BGA in the roots. BMAA was absorbed from the BGA into the cycad tree, then concentrated in the seeds, thus getting into the flour and the bats. So when the villagers consumed these items, they got a big dose of toxin.

Unfortunately, you don’t have to live on Guam and eat fruit bats to be at risk from algal toxins, however. BGA blooms are ubiquitous and can occur in fresh, salt, or brackish water and even grow on the surface crust of deserts. BGA is actually a misnomer for this species which is more accurately known as cyanobacteria. Easily recognisable as large green carpets of scum on water-bodies, cyanobacteria are one of the oldest group of organisms on earth – over 3.5 billion years old – and are thought to have created the oxygen atmosphere of the planet.

The most compelling evidence for a link between MND and cyanobacteria comes from a recent study where monkeys were fed BMAA in fruit and after 141 days, the animals developed brain tangles that are consistent with what is found in the brains of patients with MND. In support of this, a large body of epidemiological evidence continues to build for increased risk of contracting MND if you are exposed to cyanobacteria, either by living beside water bodies that are subject to frequent algal blooms, consuming seafood from contaminated water-bodies, or swimming/water skiing in contaminated water. Indeed, living beside a lake or down wind of an algal bloom can increase your risk of contracting MND by as much as 25 times and water skiing on blooms by as much as 4 times. Additionally, BMAA has been reported in the brain tissue of MND and Alzheimer’s patients from multiple locations across the globe. Further research into food webs has identified BMAA in many food sources all over the world, including shrimp, blue crab, and oysters in South Florida; mussels, oysters, and bottom-feeding fish in the Baltic Sea; traditional Asian foods such as noodles; and shark fins.

The good news is that researchers now think they know how the algal toxin can trigger neurodegeneration, and are in the process of testing a natural compound to prevent toxicity. It’s early days, but data from a Phase I clinical trials in patients with MND shows this cheap and safe drug can slow the progression of disease by as much as 85 percent. It’s also clear that exposure to cyanobacteria alone is not enough to cause disease, otherwise we’d all have MND since BGA blooms are so common (and increasing in size and frequency with increasing global temperatures).

Researchers now think that, like many neurodegenerative diseases, several factors are required to come together to cause the illness. If you have other susceptible factors, such as a faulty gene or other toxin exposures, then BMAA might be the trigger to get MND. In the meantime, the take home message is this; don’t swim in or drink green scummy water, avoid eating seafood from contaminated waters, and stay away from algal supplements like Spirulina.


Does blue-green algae cause Motor Neuron Disease?

Paul Cox has answered Likely

An expert from Brain Chemistry Labs in Pharmaceutics, Neuroscience, Botany

There is strong experimental evidence that chronic dietary exposure to the cyanobacterial toxin BMAA causes at least one motor neuron disease, e.g. Guam ALS/PDC. which afflicts the indigenous Chamorro people. 

However, ALS elsewhere likely represents a syndrome, rather than a single disease, with a variety of genetic and environmental causes. 

Data are building that exposure to the cyanobacterial toxin BMAA can be risk factor for MND elsewhere, but other genetic and environmental exposures are also important risk factors.


Does blue-green algae cause Motor Neuron Disease?

Walter Bradley has answered Unlikely

An expert from University of Miami in Neurology

Blue-green algae or cyanobacteria are one of the oldest life-forms on earth. They are a major component of harmful algal blooms (HABs) that contaminate fresh water bodies, estuaries and shallow seas around the world as a result of eutrophication (contamination with excess nutrients, especially nitrogen and phosphorus from human activity). Cyanobacteria are ubiquitous, being found in environments as diverse as the open oceans and arid deserts. Cyanobacteria produce many toxins, some of which are acutely poisonous to animals and humans who swim or play in waters with HABs, or drink from such waters. Such acute toxins, which include microcystins, nodularins, anatoxins, cylindrospermopsins and lyngbyatoxin, can lead to liver, gastrointestinal, skin and eye damage. Chronic exposure to cyanotoxins can lead to liver disease (liver cancer and non-alcoholic cirrhosis). 

Other cyanotoxins are β-methylamino-N-alanine (BMAA) and its isomers that are neurotoxic as a result of a number of different mechanisms. BMAA over-stimulates glutamate receptors on nerve cells, producing excitotoxic damage. It also becomes mis-incorporated into brain proteins, causing them to mis-fold and precipitate, leading to cell death. BMAA has been shown to be the cause of an epidemic of motor neuron disease or amyotrophic lateral sclerosis (ALS) in Guam in the 1940s to 1990s, which has been reproduced by feeding BMAA to non-human primates. Interestingly, in Guam and in these primates, BMAA also produced changes of Alzheimer’s and Parkinson’s diseases.

Because of the Guam experience, it has been suggested that chronic exposure to cyanobacteria and BMAA may be one of the environmental factors that can lead to ALS in many parts of the world. Environmental epidemiological research has found clusters of ALS patients living near to lakes with frequent HABs, has shown that living near to such lakes leads to an increased incidence of ALS, and that cyanobacteria and cyanotoxins get into aerosols that form from bubble- and wave-action, and can get into lungs of those living near these lakes. 

It is probable that cyanobacteria and cyanotoxins are responsible for some cases of ALS, particularly in those individuals who are exposed to very high doses or have a genetic predisposition to sensitivity to such toxins. However, blue-green algae are not the only cause of motor neuron disease.


Does blue-green algae cause Motor Neuron Disease?

Casey Pfluger has answered Extremely Unlikely

An expert from University of Queensland in Neurobiology, Neurology

This is a very interesting and worthwhile theory about a potential link between Blue Green Algae toxins and MND. More information and research are needed before this link can be definitively established. This theory is not yet supported by enough evidence for it to be considered an established scientific fact and the validity of the theory may well change as further research is performed. More research is needed.


Does blue-green algae cause Motor Neuron Disease?

Shyuan Ngo has answered Extremely Unlikely

An expert from University of Queensland in Neuroscience, Neurology

There have been a number of studies to link exposure to certain toxins (including those found in blue-green algae) with MND. However, correlation does not always mean causation. A lot more research is required in this area before we can definitely say that blue-green algae causes MND per se.


Does blue-green algae cause Motor Neuron Disease?

Rafael Franco has answered Extremely Unlikely

An expert from Universitat de Barcelona in Parkinson’s Disease, Alzheimer’s Disease, Antioxidants, Nutrition, Pharmacology, Asthma, Cell Biology, Biochemistry

To be sure about such “strange” hypothesis would require a lot of effort and money.

In summary “no” and wondering what supports such hypothesis(?) The theoretical number of hypothesis is infinite and 99,99% of them nonsense.


Does blue-green algae cause Motor Neuron Disease?

James Metcalf has answered Likely

An expert from Brain Chemistry Labs in Microbiology

Cyanobacteria are cosmopolitan organisms inhabiting a range of environments worldwide. They produce a wide range of toxic compounds, implicated in short term and long term human disease. They are able to synthesise a plethora of novel compounds, many with biological activity. The neurotoxic amino acid BMAA was found to be produced by cyanobacteria and to date, information suggests that the potential for production in these organisms is widespread. BMAA can be found in the brains of patients who died of motor neuron disease and is a neurotoxic compound. Furthermore, dosing of experimental animals with BMAA results in neuropathologies consistent with those found in human neurodegenerative disease. Although further work is required, the fact that BMAA can be produced by cyanobacteria, in blinded human samples it can be found in the brains of patients who died of neurological disease and not in controls, it is neurotoxic, it is found in widespread environments and that motor neuron disease is mostly sporadic, ie. no familial/genetic connection can be found, suggests that BMAA is a contributor to and a potential cause of this devastating human disease.


Does blue-green algae cause Motor Neuron Disease?

Paul  Ince has answered Unlikely

An expert from University of Sheffield in Neurology

I have nothing that would add to the views already expressed from my colleagues other than environmental exposure to cyanobacterial toxins remains a plausible but unproven theory for the aetiology of MND. There are many arguments that can be made, supported by evidence of varying quality, both for and against this theory.


Does blue-green algae cause Motor Neuron Disease?

Tim Downing has answered Likely

An expert from Mandela University in Toxicology

Our research strongly supports a link between developmental exposure to a metabolite produced by cyanobacteria (blue green algae), and progressive neurodegeneration thoughout adulthood, with symptoms typical of Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis developing over time.

Our recent work shows that a single relatively small dose of this toxin can cause long-term progressive neurodegeneration if exposure to the toxin occurs at the correct developmental stage.

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