Scientists are finding perfluoroalkyl acids in alligators, dolphins, manatees and mullet at and near Kennedy Space Center. The wildlife and human impacts remain mostly unknown. (Photo: John A. Bowden, National Institute of Standards and Technology Hollings Marine Laboratory, Charleston, SC.)

Algae toxin may be causing Alzheimer's in dolphins. Illness could signal risks for humans

In an alarming new study that has implications for people living along the Florida coast, scientists have discovered that dolphins here appear to be suffering from a condition similar to Alzheimer's disease caused by toxins from common algae.

University of Miami researchers examined the brains of 14 dolphins, some of which had beached themselves, from Florida to Massachusetts. Half of the marine mammals were found stranded in areas with frequent harmful algal blooms: the Banana River, Indian River Lagoon, the Atlantic Ocean, and the Gulf of Mexico.

Thirteen of the dolphins' brains were riddled with lesions and levels of an algae toxin called BMAA that were 1½ times what's seen in brains of humans who die of Alzheimer's disease.

"We are looking into the possibility that BMAA is causing these lesions, or at least accelerating them," said Dave Davis, lead author of the study and a research assistant professor at University of Miami's Brain Endowment Bank.

The University of Miami study, published this month in the journal PlosOne, suggests the toxin poses similar risks to humans who live along the coast or eat lots of seafood from algae-prone areas. The slow-acting toxin has uncertain health risks for coastal residents who eat or breath it for decades, the authors say. A warming planet that fuels more frequent toxic algae blooms may worsen the threat, especially in Florida, they say.

“A toxin plaguing dolphins here poses similar risks to humans who live along the coast or or eat lots of seafood from algae-prone areas.”

University of Miami study

The researchers found chronic exposure to the toxin, β-methylamino-L-alanine (BMAA), can trigger Alzheimer’s-like abnormal protein "tangles" in the brains of dolphins. The "tangles" block the ability of brain cells to function, communicate or repair themselves, so they die.

Past studies also have suggested a link between the BMAA toxin, Alzheimer's and other neurological diseases in humans, such as Parkinson’s and amyotrophic lateral sclerosis, or ALS. But the scientific jury is out on whether the toxin is a direct cause of those diseases.

The toxin is associated with common algae.

"As far as we can tell pretty much all blue-green algae (produce BMAA)," said Larry Brand, professor of marine biology and ecology at UM's Rosenstiel School of Marine and Atmospheric Science and a co-author on the study. "Some produce a lot more than others. We don't really know for sure what the function of these toxins are," he added.

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