Sprawling blooms of cyanobacteria have swathed the surfaces of lakes and oceans around the world for billions of years. But the serene, blue-green algae may be leaching a neurotoxin into the aquatic food chain, according to a study published May 3 in Proceedings of the National Academy of Sciences ( PNAS ). The report revived a nearly 50-year-old debate over the role, if any, of the toxin in the process of neurodegeneration.

In the wake of World War II a deadly neurological disease plagued the small island of Guam. The natives called it lytico-bodig (from the Spanish paralytico, meaning weakness) and it had features of Lou Gehrig's (ALS), Parkinson's and Alzheimer's diseases. Endemic to the native population (called Chamorros), the syndrome was 100 times more prevalent on Guam than anywhere else. After ruling out a genetic cause, scientists began the hunt for an environmental trigger that made Chamorros, but not immigrants, susceptible. A staple of the local cuisine raised suspicion. 

Chamorros made tortillas using flour ground from the seeds of cycads—plants often confused for ferns or palms and distantly related to both. The seeds were meticulously washed to remove toxins, such as beta-methylamino-L-alanine (BMAA), produced by cyanobacteria that inhabit cycad roots. Scientists wondered if BMAA could be causing neurodegeneration, but the concentrations ingested by the Chamorros were not sufficient to harm neurons in animal models. Huge concentrations, however, were.

In 2002 ethnobotanist Paul Cox from the Institute for Ethnobotany at the National Tropical Botanical Garden in Kalaheo, Hawaii, and neurologist Oliver Sacks from the Albert Einstein College of Medicine in New York City introduced a shocking theory about how Chamorros might be ingesting enough BMAA to damage neurons in the brain and spinal cord. The toxin, they proposed, was "biomagnified" in cycad-eating flying foxes—fruit bats. The bats ate up to 2.5 times their body weight (which can be as much as a pound for the species on Guam) in food such as cycads seeds every night and, on special occasions, Chamorros ate the bats. Cox and Sacks suggested that BMAA might accumulate in the bats' fat stores over time. But the main thrust of their hypothesis, published in Neurology, was the coincident decline in the flying fox populations on Guam and the incidence of lytico-bodig . 

Critically endangered by commercial hunting in the 1960s, the bats were virtually extinct on Guam a decade later. Carcasses imported from Western Samoa for consumption fetched up to $35 a piece. But Cox and Sacks argued the lack of indigenous cycads in Samoa meant the imports didn't contain cycad toxins, and that Chamorros were no longer being exposed to biomagnified BMAA. After a peak incidence in the mid-1960s, lytico-bodig dwindled into relative obscurity, now rarely affecting anyone born after 1960.

The theory led to a flurry of investigations into the possible role of biomagnified BMAA toxicity in neurodegenerative disease. Some researchers wondered if this tiny island in the South Pacific had revealed an elusive environmental trigger for neurodegenerative disease elsewhere in the world—the "Rosetta stone" of neurodegeneration. Since then many have spent years trying to confirm or refute the hypothesis. Believers, like Cox, think the potential for biomagnified BMAA to kill neurons should be studied in the interest of public health. They've cited elevated levels of BMAA both in Chamorro brains and in those of Alzheimer's disease patients in Canada to support their stance. Skeptics, such as neurologist John Steele of Guam Memorial Hospital, think BMAA research constitutes a "scientific misadventure," leaving the real cause of lytico-bodig unknown. They've looked for BMAA in similar brain samples, and haven't seen it.

"I think they should be skeptical," says Cox of Steele and others who think the hypothesis is wrong. "It's just a hypothesis, and it could be wrong. A lot more research needs to be done to validate the hypothesis."

But pouring valuable resources into what might be a red herring, Steele worries, detracts from more important research into the Guam disease's cause.

4 Comments

1. 1. katesisco 10:15 AM 5/29/10

   pandora's locks by j alexander has detailed the results of foreign aquatic invaders; the quagga especially resulting consumption of phytoplankton depositing their excretia on the lake floor where it feeds Cladophora algae from the phosphorus. It has now spread to cover the benthic zone; the discovery in 2006 by scientists showed that the deadly microcystins were present in air even without an algae bloom present. Toxic cyanobacteria are here to stay.
   Perhaps the search for an introduced specie may be better able to explain the cyanobacteria spread in Guam.

   Reply | Report Abuse | Link to this

2. 2. ironjustice 04:41 PM 5/29/10

   One might wonder WHAT they DID eat NOW that the bats were all killed off ? DID? their meat intake / iron intake go DOWN?
   The Guam heavy metal connection has already been hypothesised (Mitchell J 2000) AND a human model of heavy metal induced ALS discovered. "Iron Overload Gene Possible ALS Risk Factor" "Iron chelator therapy for Amyotrophic Lateral Sclerosis"
   

   Reply | Report Abuse | Link to this

3. 3. Lou Sian 02:51 AM 5/30/10

   Lytigo bodig on Guam is a famous disease among neurologists. It's a tragic disease in which the patient slowly deteriorates, while his mind & spirit are intact. It's like being buried alive in a coffin with a small window to look out at the world. It's heartbreaking, and yet Guam has no adequate facilities or support community to help alleviate the suffering experienced by both the patient & his family caregivers. While researchers are trying to understand the cause of this disease, more research should be developed to try to ease the burden & suffering experienced by the patients & family caregivers. We need help!

   Reply | Report Abuse | Link to this

4. 4. SALJNL 02:21 AM 1/12/11

   Lytico-Bodig (ALS-PDC)has been found in Umatac, Guam, in Papua New Guinea and Honshu, Japan. The Flying Fox bats of Guam and Papua New Guinea and the Japanese Macaque all spend time at the limestone lakes and caves with moonmilk walls full of Tellurium. Tellurium is found in higher concentrations on the ocean floor, and where the ocean floor rises to the surface on volcanic islands. The bats are eaten by humans and the Macaque body parts are saved for worship in Honshu, Japan. Tellurium is stored in bone and some soft tissue. In the moonmilk is Cyanobacteria, Aspergillus, and Acinomycetes. Cyanobacteria have been linked to Alzheimer's and ALS. Aspergillus oryzae makes the L-Dopa medication so useful to Parkinsonians. Aspergillus terreus makes Lovastatin that "Unmasks Parkinson's Disease" making the symptoms worse in those with the disease. Fibronectin staining of Alzheimer Diseased Brains shows filamentous micro-organisms which may belong to actinomycetes PMID 1421118. Dr. Andrew J. Larner wrote Alzheimer's Disease, Kuf's Disease, Tellurium and Selenium in 1997. Probing Protein Stability with Non-Natural Amino Acids by Nediljko Budisa and Greta Pifat in 1997 describes Tellurium and protein misfolding. ALS-PDC or Lytico-Bodig disease has symptoms of ALS and Parkinson's and Alzheimer's. All three diseases are protein misfolding diseases. I think if the moonmilk is tested in these three places one may find the Tellurite-resistant organisms responsible for Lytico Bodig Disease, as well as the reason for many other protein misfolding diseases.

   Reply | Report Abuse | Link to this