Riccardo Liguori A new study from the University of Miami analyzed the brains of twenty bottlenose dolphins found dead in Florida, detecting the same abnormalities as human Alzheimer's
They are intelligent, social, and capable of navigating with astonishing precision. Yet increasingly, dolphins are washing up on Florida’s shores, disoriented or already lifeless. For years, scientists have wondered why. Now a study published in Nature Communications Biology suggests an explanation: these animals may be developing a form of Alzheimer’s disease, triggered by toxins produced by algal blooms.
The research team, led by David A. Davis from the University of Miami along with laboratories at the Brain Chemistry Labs in Wyoming, analyzed the brains of twenty bottlenose dolphins found dead along the Indian River Lagoon, an extensive coastal area that has experienced cyanobacterial blooms for years. The findings reveal that during peak bloom periods, dolphin brains contained up to 2,900 times more 2,4-diaminobutyric acid (2,4-DAB), a neurotoxin produced by microscopic algae, compared to months without blooms.
This substance, chemically similar to β-N-methylamino-L-alanine (BMAA), is known for its effects on the nervous system. In the analyzed dolphins, researchers observed β-amyloid plaques, tau protein tangles, and TDP-43 inclusions: the same abnormalities found in the brains of humans suffering from Alzheimer’s. Additionally, 536 altered genes were identified, many of which are involved in synaptic functions, the blood-brain barrier, and neuronal inflammation mechanisms.
Cyanobacterial blooms—phenomena that turn waters green and release toxic compounds—intensify with rising temperatures and excess nutrients from agricultural and urban runoff. In an environment like the Indian River Lagoon, warmed and rich in nitrogen and phosphorus, algae proliferate rapidly, releasing substances into the sea that accumulate in the food chain until reaching apex predators like dolphins.
“These animals are true environmental sentinels,” Davis explained. “They show us how toxic substances present in marine ecosystems can reflect on the health of organisms, including humans.”
Global warming and water pollution are thus creating a dangerous biological entanglement. Warmer seas favor toxic blooms, toxins accumulate in fish and marine mammals, and the long-term damage affects the brain.
The study does not prove that algal toxins are the sole cause of Alzheimer’s, but it indicates they may be an environmental risk factor.
Source: Nature Communications Biology
