Florida Dolphins Show Alzheimer’s-Like Brain Changes Linked to Toxic Algal Blooms
Summary
- A collaborative study involving University of Miami Miller School of Medicine researchers discovered that dolphins living in Florida’s Indian River Lagoon show brain changes similar to Alzheimer’s disease.
- The study is one of the first to connect neurotoxins found in algal blooms directly to brain changes associated with Alzheimer’s-like disease in a wild marine mammal.
- The Miller School’s Dr. David Davis says dolphins are “sentinel species” and may reveal clues to neurodegenerative diseases like Alzheimer’s in humans.
A new study in Nature Communications Biology has discovered that dolphins living in Florida’s Indian River Lagoon show brain changes similar to Alzheimer’s disease.
The collaborative study, which included scientists from the University of Miami Miller School of Medicine, Hubbs-SeaWorld Research Institute (HSWRI), Brain Chemistry Labs, the University of Miami’s Rosenstiel School of Marine, Atmospheric, and Earth Science and Blue World Research Institute, found that dolphins exposed to harmful algal blooms carried high levels of a toxin in their brains and showed warning signs of neurodegeneration.
A New Alzheimer’s Disease Connection
The study is one of the first to connect neurotoxins found in algal blooms directly to brain changes associated with Alzheimer’s-like disease in a wild marine mammal. It also illustrates how warm water and nutrient pollution, which fuel these blooms, may impact wildlife health.
“Dolphins serve as a sentinel species. They naturally develop amyloid and tau pathology, and their brains reveal how environmental stressors like harmful algal bloom toxins may accelerate neurodegenerative processes,” said David Davis, Ph.D., a neurotoxicologist, associate director of the Brain Endowment Bank and assistant research professor in the Department of Neurology at the Miller School. “We observed transcriptomic parallels between dolphins exposed to algal toxins and human Alzheimer’s disease, especially in pathways affecting neuronal communication and the blood–brain barrier.”
As our climate warms, algal blooms are becoming more frequent and severe, posing significant risks to marine ecosystems and public health. The study builds on ongoing research by the Brain Endowment Bank that investigates the impact of neurotoxins from algal blooms and their association to Alzheimer’s disease.
Algal Blooms Associated with Toxins
During bloom seasons, stranded dolphins were found to have 2,900 times more of the toxin 2,4-diaminobutyric acid (2,4-DAB) in their brains compared to dolphins stranded outside of bloom seasons. Alongside these toxins, researchers observed changes in brain chemistry and tissue that mirror early Alzheimer’s disease, including abnormal protein build-up and shifts in key genes linked to memory, brain health and Alzheimer’s disease risk.
“HABs are known to generate the isomers BMAA, DAB and AEG, they can biomagnify up the food chain, they have been documented in the brains of dolphins exposed to HABs and these brains exhibit characteristics of neurodegenerative diseases,” said Larry Brand, Ph.D., a study co-author and professor of marine biology and ecology at the Rosenstiel School of Marine, Atmospheric, and Earth Science.
The results also align with recent research showing that ecosystem disruption in Florida’s Indian River Lagoon has led to major changes in dolphin diet and prey availability.
“These results are concerning because dolphins share coastal waters with humans and face many of the same environmental risks we do,” said Wendy Noke Durden, research scientist with HSWRI. “We’re only beginning to understand how environmental change and toxin exposure affect the health of marine mammals and what that might mean for people who share these waters. Seeing Alzheimer’s-like changes in dolphins raises questions about whether similar problems exist in other species both in the U.S and around the world.”
This work was supported by funds from the sale of Discover Florida Oceans license plate, the Brevard County Tourism and Development Council, the Herbert W. Hoover Foundation and the SeaWorld Busch Gardens Conservation Fund.
Tags: Alzheimer's disease, blood-brain barrier, Brain Endowment Bank, dementia, Department of Neurology, Dr. David Davis, neurodegenerative diseases, neurology, Newsroom