Dolphins With Alzheimer’s? Toxic Algae Blooms May Be to Blame

By | April 1st, 2019

Scientists have found something troubling off the coasts of Florida and Massachusetts: The brains of beached dolphins are showing signs of beta-amyloid, the protein that accumulates in toxic levels in the brains of Alzheimer’s patients and is thought to trigger nerve death, leading to symptoms like memory loss and confusion.

The Physical Signs of Alzheimer’s in Dolphins

“We found β-amyloid plaques and damaged neurons in brain tissues from dolphins that had died on the beaches of Florida and Massachusetts,” said David Davis, Ph.D., at the University of Miami Neurology Department.

This is not the first time researchers discovered signs of Alzheimer’s in mammals. In 2017, dolphins washed up on the shores of Spain also showed signs of beta-amyloid plaques, the first wild animals found to have signs of the neurodegenerative disease. A few months before that, chimpanzees in captivity were found to have signs of plaques and tau tangles, another biomarker of Alzheimer’s. Those animals did not show symptoms of the disease, as far as researchers could tell.

But the beached dolphins may have symptoms along with the physical signs of Alzheimer’s, researchers theorized. “The … question is whether these marine mammals experienced cognitive deficits and disorientation that led to their beaching,” said ethnobotanist Paul Alan Cox at the Brain Chemistry Labs in Jackson Hole, Wyoming.

Are Toxic Algae Blooms Triggering Alzheimer’s?

Alongside the beta-amyloid plaques, researchers also found signs of an environmental toxin produced by the cyanobacterial blooms, produced by a blue-green algae that grow in warm water with ample sunlight and is encouraged by fertilizer run-off. The bacteria can be found in drinking water that hasn’t been properly treated, consumption of fish from contaminated waters and recreational contact from swimming and water sports, according to the North American Lake Management Society. The algae occur in both fresh and saltwater. Some types of cyanobacteria have been linked to neurological issues in humans.

Signs like these in dolphins could act as a red flag for humans.

What Alzheimer’s in Dolphins Can Teach Humans

“Dolphins are an excellent sentinel species for toxic exposures in the marine environment,” said Deborah Mash, Ph.D., co-author of the study. “With increasing frequency and duration of cyanobacterial blooms in coastal waters, dolphins might provide early warning of toxic exposures that could impact human health.”

The study, published in the journal PLOS ONE, was small, but 13 of the 14 stranded dolphins showed signs of both beta-amyloid and cyanobacteria exposure. They were found along the East Coast in areas with frequent cases of algae blooms: the Banana River, Indian River Lagoon, the Atlantic Ocean, and the Gulf of Mexico. But is the algae exposure causing the signs of Alzheimer’s? “Until further research clarifies this question, people should take simple steps to avoid cyanobacterial exposure,” said Cox.

How to Avoid Toxic Algae Exposure

Blue-green algae blooms usually occur in late summer and early fall. Experts urge people to avoid visible blooms — bodies of water with blue, green or brown foam on top — and to keep pets from making contact with water showing signs of cyanobacteria.

“We cannot say for sure that chronic exposure to cyanobacterial blooms can trigger Alzheimer’s in humans, but it is a risk that I personally am unwilling to take,” oceanographer Larry Brand at Rosenstiel School of Marine Atmospheric Science cautions.

[ Next: Signs of Alzheimer’s Detected in Species Other Than Humans for First Time ]


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