The Brains of Stranded Dolphins Show Signs of Alzheimer’s

Dolphins and whales often become stranded on land or in shallow waters. This can happen to individual animals, a mother and calf, and sometimes groups. The reasons why aren’t always understood. A recent study investigated possible brain pathology behind these incidents and found that some of the animals showed signs of a common human disease.

Researchers across several Scottish universities and the Moredun Research Institute examined the brains of 22 toothed whales, or odontocetes, that had become stranded in waters off the coast of Scotland. The findings, published in the European Journal of Neuroscience, showed that some of the animals had amyloid-beta plaques, hallmarks of Alzheimer’s.


Frank Gunn-Moore, study co-author and professor from the University of St Andrews, says, “I have always been interested in answering the question: do only humans get dementia? Our findings answer this question as it shows potential dementia associated pathology is indeed not just seen in human patients.”

The research involved five species: Risso’s dolphins, white-beaked dolphins, bottlenose dolphins, long-finned pilot whales, and harbor porpoises. The researchers were looking for amyloid-beta plaques, the accumulation of phosphor-tau, and gliosis. Three of the animals, which were all from a different species, were found to have both amyloid-beta plaques and several other dementia-related hallmarks within their brains.


The researchers say this could provide more evidence for the sick-leader theory, which involves a healthy pod getting stranded due to a group leader that has become confused or lost. However, there’s no way of knowing, based on this study, if the animals with signs of Alzheimer’s actually have the same cognitive deficits as people with the disease.

Dr. Mark Dagleish, lead researcher from the University of Glasgow, explains, “These are significant findings that show, for the first time, that the brain pathology in stranded odontocetes is similar to the brains of humans affected by clinical Alzheimer’s disease. While it is tempting at this stage to speculate that the presence of these brain lesions in odontocetes indicates that they may also suffer with the cognitive deficits associated with human Alzheimer’s disease, more research must be done to better understand what is happening to these animals.”


The team says more research is also needed to determine if these brain changes have anything to do with stranding.

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