Toxins from algal blooms may cause Alzheimer's-like brain changes

January 20, 2016 by Melissa Healy, Los Angeles Times
Taken in October 2011, the worst algae bloom that Lake Erie has experienced in decades. Credit: NASA Earth Observatory

A group of villagers on the Pacific island of Guam has offered some key insight into the role that an environmental toxin may play in brain changes that are a hallmark of Alzheimer's disease. And scientists studying that neurotoxin appear to have found a possible antidote.

In some Chamorro residents in Guam, Army physicians in the 1950s identified a paralytic disease that had similarities to Parkinson's disease, amyotrophic lateral sclerosis (ALS, better known as Lou Gehrig's disease) and dementia. Scientists later observed that upon the death of those affected by Guamanian amyotrophic lateral sclerosis-parkinsonism-dementia complex, their brains were found to be riddled with the same kinds of amyloid protein clumps and tangles of neural fibers that are routinely seen in the brains of those with Alzheimer's disease.

In hunting for the cause of the Guamanian affliction, scientists' suspicions have fallen on an environmental toxin-the amino acid beta-N-methylamino-L-alanine (or L-BMAA). Produced by a wide range of cyanobacteria, L-BMAA is plentiful in algal blooms and can be found in some sea creatures-sharks, bottom-dwelling fish and shellfish-who ingest such algae. It has been implicated in the elevated rates of ALS among soldiers in the 1991 Persian Gulf War, who may have inhaled high concentrations of L-BMAA in desert dust.

Among the Chamorro who were studied, L-BMAA had made its way in high doses into their diets, largely in the tissue of flying foxes. It could take years of eating tainted meat or flour before a villager might develop the disabling disease. But even when outsiders came to Guam and ate what locals ate, they were likely to become ill-which suggested an environmental toxin might be to blame.

With those clues in hand, scientists from the Institute for EthnoMedicine in Jackson Hole, Wyo., decided to test the effects of ingested L-BMAA in vervets, a monkey native to Africa. Over 140 days, they fed one group of vervets fruit laced with L-BMAA-in a dose that would approximate a lifetime dose of L-BMAA for a Chamorro villager. Another group got a dose one-tenth as high, and a third group got the high dose of L-BMAA and an equal dose of an amino acid supplement called L-serine. A fourth group got fruit with a neutral placebo added.

After the 140 days, tangles and were found in the brain tissues of all of the vervets who consumed L-BMAA. But the vervets that got the L-serine with the L-BMAA fared far better: They had neurofibrillary tangles that were significantly less dense than those seen in monkeys that got L-BMAA alone.

The new report appeared Tuesday in the British journal Proceedings of the Royal Society B: Biological Sciences.

The human body synthesizes L-serine-an amino acid that is key to muscle growth, a healthy immune system and the metabolism of fats, fatty acids and cell membranes. In collaboration with the Institute for EthnoMedicine, Phoenix Neurological Associates is currently conducting a preliminary clinical trial of L-serine supplementation in people dagnosed with ALS. That trial is expected to produce results by the end of this year.

Deborah Mash, director of the University of Miami Brain Endowment Bank and coauthor of the study, said its findings offer strong evidence that L-BMAA causes neurodegenerative disease-a link long suspected but still a surmise.

"The tangles and amyloid deposits produced were nearly identical to those found in the brain tissue of the Pacific Islanders who died from the Alzheimer's-like disease," she said.

The findings also offer tantalizing evidence that a readily available dietary supplement might help counter the neurodegenerative effects of some environmental toxins, and may help patients with diseases such as Parkinson's, ALS or Alzheimer's.

Ethnobotanist Paul Alan Cox, one of the study's authors, said that "much more research is needed" on the safety and effectiveness of L-serine before it would be wise for humans to begin using the supplement to ward off disease. But he said vervets, who quickly developed the seen in Alzheimer's disease, "may prove useful in evaluating other potential new Alzheimer's drugs."

The Institute for EthnoMedicine is a nonprofit research organization dedicated to discovering new cures for neurodegenerative diseases from studies of indigenous peoples. It's established a consortium of 50 scientists operating at 28 institutions in 10 countries.

Explore further: Neurotoxin found in commercial seafood

More information: Dietary exposure to the environmental toxin BMAA triggers neurofibrillary tangles and amyloid deposits in the brain, Proceedings of the Royal Society B: Biological Sciences, rspb.royalsocietypublishing.or … .1098/rspb.2015.2397

Related Stories

Neurotoxin found in commercial seafood

June 4, 2015
Popular commercial seafood purchased from Swedish supermarkets at the Stockholm region contains Beta-Methylamino-L-Alanine (BMAA), shows a doctoral thesis from Stockholm University. BMAA is a naturally-occurring amino acid ...

New mechanism for protein misfolding may link to ALS

September 25, 2013
Proteins play important roles in the human body, particularly neuroproteins that maintain proper brain function.

Breakthrough discovery links blue-green algae with motor neuron disease

September 26, 2013
(Medical Xpress)—A recently identified link between a toxic amino acid found in blue-green algae and several motor neuron diseases could help researchers devise a therapy for the fatal conditions.

Neurotoxins in shark fins: A human health concern

February 23, 2012
Sharks are among the most threatened of marine species worldwide due to unsustainable overfishing. Sharks are primarily killed for their fins alone, to fuel the growing demand for shark fin soup, which is an Asia delicacy. ...

Study finds cerebrovascular disease to be major determinant of psychosis in patients with Alzheimer's

January 5, 2016
About half of all patients with Alzheimer's disease develop symptoms of psychosis, such as delusions or hallucinations.

Negative beliefs about aging predict Alzheimer's disease

December 7, 2015
Newly published research led by the Yale School of Public Health demonstrates that individuals who hold negative beliefs about aging are more likely to have brain changes associated with Alzheimer's disease.

Recommended for you

Study reveals connection between microbiome and autoimmune disorders

October 23, 2017
Many people associate the word "bacteria" with something dirty and disgusting. Dr. Pere Santamaria disagrees. Called the microbiome, the bacteria in our bodies have all kinds of positive effects on our health, Santamaria ...

Engineered protein treatment found to reduce obesity in mice, rats and primates

October 19, 2017
(Medical Xpress)—A team of researchers with pharmaceutical company Amgen Inc. report that an engineered version of a protein naturally found in the body caused test mice, rats and cynomolgus monkeys to lose weight. In their ...

New procedure enables cultivation of human brain sections in the petri dish

October 19, 2017
Researchers at the University of Tübingen have become the first to keep human brain tissue alive outside the body for several weeks. The researchers, headed by Dr. Niklas Schwarz, Dr. Henner Koch and Dr. Thomas Wuttke at ...

Cancer drug found to offer promising results in treating sepsis in test mice

October 19, 2017
(Medical Xpress)—A combined team of researchers from China and the U.S. has found that a drug commonly used to treat lung cancer in humans offers a degree of protection against sepsis in test mice. In their paper published ...

Tracing cell death pathway points to drug targets for brain damage, kidney injury, asthma

October 19, 2017
University of Pittsburgh scientists are unlocking the complexities of a recently discovered cell death process that plays a key role in health and disease, and new findings link their discovery to asthma, kidney injury and ...

Study reveals key molecular link in major cell growth pathway

October 19, 2017
A team of scientists led by Whitehead Institute has uncovered a surprising molecular link that connects how cells regulate growth with how they sense and make available the nutrients required for growth. Their work, which ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.