Researchers are now linking some ALS incidence with folks who live near large bodies of water, a new piece in Scientific American points out. It writes:
About five years ago, doctors at a New Hampshire hospital noticed a pattern in their ALS patients—many of them, like Gilmore, lived near water. Since then, researchers at Dartmouth-Hitchcock Medical Center have identified several ALS hot spots in lake and coastal communities in New England, and they suspect that toxic blooms of blue-green algae—which are becoming more common worldwide—may play a role.
Now scientists are investigating whether breathing a neurotoxin produced by the algae may raise the risk of the disease. They have a long way to go, however: While the toxin does seem to kill nerve cells, no research, even in animals, has confirmed the link to ALS.
There is, after all, no known cause for Lou Gehrig’s disease: Some 90 to 95 percent of ALS patients carry no known genetic mutation; researchers have generally concluded that there’s some link between environment and genetic predisposition that causes the grave disease. The Scientific American piece continues:
“There’s a growing awareness of the importance of gene/environment interactions with neurodegenerative diseases. There is more interest in examining environmental exposures, including exposures to cyanobacteria, as possible risk factors for sporadic ALS,” said Paul Alan Cox, director of the nonprofit Institute of Ethnomedicine in Wyoming, which focuses on treatments for ALS and other neurodegenerative diseases.
Cyanobacteria—some of the oldest organisms on the planet—can occur wherever there is moisture. Blooms are fed largely by nutrients in agricultural and urban runoff.
Some cyanobacteria produce toxic compounds that can sicken people. In August, hundreds of thousands of people in Toledo, Ohio, were left without tap water for days when toxins from an algal bloom in Lake Erie were found in the water supply.
While the cyanobacteria toxin that prompted the Toledo water crisis can cause diarrhea, intestinal pain and liver problems, other toxins produced by the blue-green algae can harm the nervous systems of humans and wildlife.
Scientists have long suspected that a cyanobacteria toxin could play a role in some forms of ALS. After World War II, U.S. military doctors in Guam found that many indigenous Chamorro suffered from a rapidly progressing neurological disease with symptoms similar to both ALS and dementia. Years later, scientists found the neurotoxin BMAA in the brains of Chamorro people who died from the disease. Cyanobacteria that grow on the roots and seeds of cycad trees produce the toxin.
Cox, a researcher in Guam in the 1990s, hypothesized that BMAA worked its way up the food chain from the cycad seeds to bats to the Chamorro who hunted them. But Cox and his colleagues also found BMAA in the brains of Canadian Alzheimer’s patients who had never dined on Guam’s fruit bats. In patients who had died from other causes, they found no traces of it. The source of the BMAA in the Canadians remains unknown.
