Could cognitive deficiencies resembling Alzheimer’s in pod leaders be to blame for the phenomenon of whale and dolphin strandings by luring groups into shallow waters? In a recent study, degenerative alterations in dolphin brain tissue were shown to mimic those in Alzheimer’s disease patients who are human.
The current study builds on a significant 2018 study that provided the first concrete evidence of Alzheimer’s-like disease in a wild animal’s brain. The 2018 study’s co-authors, Frank Gunn-Moore and Mark Dagleish of the University of Glasgow carried out the largest study to date on dementia in dolphins.
22 animals, representing five different species—dolphins, Risso’s long-finned pilot whales, white-beaked dolphins, harbor porpoises, and bottlenose dolphins—had their brain tissue examined. In the waters off the Scottish coast, all of the creatures were discovered to be stranded.
It was discovered that three animals, representing three separate species, each possessed specific pathological symptoms of Alzheimer’s disease. These included the development of amyloid protein plaques, the buildup of tau protein tangles, and the appearance of gliosis, a type of brain damage.
Do only humans suffer from dementia? is a question that has long piqued my curiosity. said Gunn-Moore. Our findings provide an answer to this query since they demonstrate that dementia-related disease can exist in non-human patients as well.
Naturally, the results cannot prove that these specific animals had the kinds of cognitive impairments we typically associate with dementia. They can only demonstrate that animals indeed exhibit pathological traits that are similar to those exhibited in dementia patients in humans.
The study does, however, provide strong support for a theory that is frequently put forth to explain the huge strandings of whales and dolphins. The “sick-leader syndrome” idea contends that a leader who has cognitive impairment may be to blame for directing its pod into shallow waters, ultimately leading to mass stranding incidents.
After a multidisciplinary team of researchers looked into the mass stranding of seven sperm whales off the Italian coast a few years ago, the theory was initially put forth. According to that study, a viral illness may have affected the whales’ ability to navigate, and the eldest member of the pod’s deteriorating health may have caused the group to be lead into the waters where the animals were ultimately trapped.
The authors of this new study hypothesize that some mass-stranding episodes may be influenced by cognitive loss brought on by neurological conditions. The study finds that bewilderment and disorientation are the early signs of Alzheimer’s-related deterioration in humans. Therefore, it is plausible to hypothesize that whale and dolphin pod leaders could entice groups into stranding incidents if they had similar neurological degeneration.
The study’s lead author, Tara Spires-Jones of the University of Edinburgh, is careful not to overstate the results. She stated that more research is necessary to examine the connection between dementia and stranding episodes.
“We were fascinated to see brain changes in aged dolphins similar to those in human aging and Alzheimer’s disease,” said Spires-Jones. “Whether these pathological changes contribute to these animals stranding is an interesting and important question for future work.”
