Guam tree, fruit bats linked to high count of neurological cases
By Jan TenBruggencate
Advertiser Science Writer
New research being conducted in Hawai'i is suggesting a link between neurological diseases like Alzheimer's and a poison produced by a kind of cyanobacteria, or blue-green algae.
Paul Cox, Sandra Banack, Patty Stewart
The research started as an inquiry into the cause of a neurological disease in Guam natives who ate a traditional Chamorro diet. The work has been conducted by ethnobotanist Paul Alan Cox and biochemist Susan Murch, of the National Tropical Botanical Garden on Kaua'i, and Sandra Anne Banack, a zoology professor at California State University at Fullerton. A report was to be published today in the Proceedings of the National Academy of Sciences.
The fruit of the Guam cycad tree and the bats that eat it are transmitting a toxic compound linked to neurological disease, research shows.
The researchers found that the Guam natives who came down with a nervous system disease had high levels of a toxic compound known as BMAA in their brain tissue. The disease is ALS-PDC, which refers to a complex of similar diseases that include amyotropic lateral sclerosis or Lou Gehrig's disease, Parkinson's disease and Alzheimer's disease.
It turns out, Cox said, that cyanobacteria in cycad tree roots produce BMAA, transfer it to the cycad tissue and its seeds, and then to flying foxes — or fruit bats — that eat the cycad seeds. At each stage, the toxin appears in higher levels, a process called biomagnification.
When Chamorros who ate a traditional diet began eating more of the foxes, in part because of the introduction of guns that made hunting them easier, the Chamorros began getting more of the poison in their systems. There were a significant number of cases in the last half of the 1900s. Today, one of the native foxes is extinct and the other rare, and the number of new cases of ALS-PDC has dropped off.
But in a recent development, the scientists found that two Canadians who died of Alzheimer's Disease had the same toxin in their brains as Chamorros. Cox said the researchers studied brain tissue from 15 Canadians as a control group. They found BMAA in two of the Canadians. And it turned out both of them had died of Alzheimer's.
"Cycads don't grow in Canada," Cox said, but the culprit cyanobacteria are found "all over the world." They can often form symbiotic relationships with plants, living within plant tissues while they assist the plants in putting nitrogen into a plant-usable form.
One question now is whether something in those Canadians' diet contained biomagnified BMAA.
Cox and his team also are studying villagers on the Kii Peninsula of Honshu Island in Japan, where there are cycads but no flying foxes, and there are reports of clusters of neurological diseases. They also have an interest in reports of the diseases in villages in Indonesia's easternmost province, Irian Jaya, also known as Papua.
"It's like a detective story," Cox said.
He said science should look into the possibility that certain forms of neurological disease are associated with biomagnification of cyanobacteria toxins.
"I think now that we have shown a pretty strong case" that it's a possible factor, Cox said.
Reach Jan TenBruggencate at jant@honoluluadvertiser.com or (808) 245-3074.
