Dolphins at Risk of Suffering from Alzheimer's, Says Scottish Researchers

According to Scottish researchers, dolphins may have Alzheimer's disease. Three species, including a bottlenose dolphin, a long-finned pilot whale, and another, were discovered to have the disease's symptoms.

(Photo : Ranae Smith/Unsplash)

Dolphin Study

A study has discovered the characteristic signs of Alzheimer's disease in three species of stranded cetaceans, including a bottlenose dolphin and a long-finned pilot whale, off the coast of Scotland.

Alzheimer's disease has not been found to spontaneously arise in any species other than humans, despite various forms of dementia being quite regularly detected in other animals.

But postmortem examinations of 22 toothed whales, or odontocetes, conducted by researchers from the Universities of Glasgow, St. Andrews, and Edinburgh, as well as the Moredun Research Institute in Scotland, revealed three crucial brain changes linked to human Alzheimer's disease in three of the animals.

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Brain Deterioration

(Photo : Rudney Uezu/Unsplash)

The origin of this brain deterioration is unknown to scientists, but it may lend credence to one idea explaining why some pods or groups of whales and dolphins become stranded in shallow water.

However, Alzheimer's-like brain changes could lend credence to the "sick leader" theory, according to which most healthy cetaceans strand themselves because they follow a group leader who has become disoriented or lost. Some mass strandings have been linked to rising anthropogenic noise in the oceans.

Three of the 22 stranded odontocetes, a white-beaked dolphin, a bottlenose dolphin, and a long-finned pilot whale, a member of the dolphin family, showed evidence of Alzheimer's, according to the researchers.

The study, published in the European Journal of Neuroscience, found that all three patients had three signs of Alzheimer's disease in humans and were old for their species. Another protein called tau had gathered into tangles inside the neurons, abnormal levels of beta-amyloid protein had formed into plaques that disrupt neurons in the brain, and there was an accumulation of glial cells, which causes inflammation of the brain.

Dr. Mark Dagleish, a pathologist and the study's principal investigator from the University of Glasgow, said it was impossible to say if this damage would result in the same cognitive problems linked to Alzheimer's disease in humans. Studying the individual animals while they were alive would be necessary to ascertain whether the dolphins and whales had Alzheimer's.

According to him, these important discoveries demonstrate for the first time that the brain pathology of stranded odontocetes is comparable to that of people with clinical Alzheimer's disease. While it is tempting to assume at this point that odontocetes may also have cognitive problems linked to Alzheimer's disease in humans because they have these brain lesions, additional research is necessary to understand what is occurring to these animals fully.

Understanding How Dolphin Brains Work

Because they can live for many years after they stop being reproductively active, like humans, but unlike many other species, whales and dolphins may exhibit Alzheimer's-like brain lesions. A 2020 study that discovered that deep-diving beaked whales are more prone to diseases similar to Alzheimer's because of the hypoxia-low amounts of oxygen in their bodily tissues-caused by their deep-ocean foraging offered another probable explanation.

Also recently discovered to have Alzheimer's symptoms was a 40-year-old bottlenose dolphin in captivity.

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