Dolphins could develop Alzheimer’s disease, researchers say

Several species of dolphins may be suffering from Alzheimer’s disease, according to a new study.

The research could help explain the widespread but puzzling phenomenon of mass dolphin strandings, which occur when multiple dolphins wash ashore, often resulting in their deaths.

The brain of 22 beached toothed whales, known as odontocetes and which include dolphins, have been studied by researchers at several universities in the UK, according to a study published Dec. 13 in the European Journal of Neuroscience. Five distinct species were examined, including the bottlenose dolphin, Risso’s dolphin and the harbor porpoise.

Through a series of diagnostic tests, the researchers looked for telltale signs of Alzheimer’s disease, a brain disorder that gradually destroys memory and other cognitive functions, according to the study.

All of the toothed whale brains had amyloid plaque, which are lesions made up of protein deposits. The plate is one of define characteristics of Alzheimer’s. Three of the species, in addition to plaque buildups, had phosphorylated tau in their neurons, another sign of Alzheimer’s disease, meaning these species develop an Alzheimer’s-like disease “spontaneously”, said Researchers.

The degenerative disease could contribute to mass strandings of some dolphins and other toothed whales, researchers have said.

Their findings support the “sick leader” theory, which states that a pod of healthy dolphins will follow a sick leader until they die due to “high social cohesion”, the researchers said, although they added that further research was needed.

The researchers did not immediately respond to a McClatchy News request for comment.

“We were fascinated to see brain changes in older dolphins similar to those of human aging and Alzheimer’s disease,” Tara Spires-Jones, a professor at the University of Edinburgh and a member of the research team, told The Guardian. “Whether these pathological changes contribute to the stranding of these animals is an interesting and important question for future work.”

In the future, toothed whales may prove more useful than nonhuman primates for studying Alzheimer’s disease due to similarities shared by humans and marine mammals, researchers said.

Whales, dolphins and porpoises have been more stranding worldwide, according to a 2020 study published in the journal Scientific Reports, although the cause of the phenomenon is not known. Oceanographic events, pollution and disease have already been put forward as potential causes.