Petlife logo

Dolphins and Alzheimer’s: A Combination Linked to Strandings?

Recent studies on five species of oceanic dolphins have found markers of Alzheimer’s Disease.

By Jenna DeedyPublished 4 months ago 4 min read
Dolphins and Alzheimer’s: A Combination Linked to Strandings?
Photo by NOAA on Unsplash

Trigger Warning: This article will mention themes that many readers may find to be upsetting such as Alzheimer’s Disease and death. If these themes upset you, click out of the article.

Mass cetacean strandings have always happened long before our ancestors' recorded history. Yet, how and why they strand in large numbers remains a mystery. While researchers have found links between naval sonar and beaked whale strandings. Some point to the possibility of animals falling ill at sea while some point to the animals’ accidental consumption of plastic waste. However, most mass strandings don’t provide the clearest clues why they happen.

Recently, scientists have suggested a new theory that could solve the mystery of why mass cetacean strandings happen. In a journal published by the European Journal of Neuroscience on December 13th, 2022, a study was done on the remains of twenty-two animals comprising five different species by using immunohistochemistry to investigate the presence or absence of neuropathological markers of Alzheimer’s disease. These markers are amyloid-beta plaques, phospho-tau accumulation, and gliosis.

What’s Alzheimer’s Disease?

The most common cause of neurological disability among elderly people, Alzheimer’s affects 30 million people over 50 years old worldwide. It causes impaired memory, learning, and communication. Despite ongoing research since its discovery more than a century ago, there’s currently no effective treatment or cure to prevent it from progressing. It now appears that it may affect cetaceans, too.

Why Do You Say That?

At least five species of toothed whales, known as “Odontocetes”, share several traits with humans, which includes the ability of females to undergo menopause, and live almost beyond their calf-rearing years, which could explain why they have the potential to become susceptible to age-related health issues.

Onto The Study

Because scientists were wondering if humans weren’t the only species that can develop Alzheimer’s and dementia, they made their aim to examine similar markers in stranded cetaceans. In order to do that, the researchers got a hold of brain samples that were collected from twenty-two cetaceans that were stranded and died off the coast of Scotland. These samples were trimmed and placed into large cassettes before being processed through alcohol and wax. After this, the samples were sectioned and mounted onto glass microscope slides for examination.

The five species that were chosen for the study were Risso’s dolphins. Long-finned pilot whales, white-beaked dolphins, harbor porpoises, and a single Atlantic bottlenose dolphin. The samples that came from these chosen species were mainly based on recorded evidence of old age such as worn or lost teeth, increase in the white brain matter, age derived from a historical examination of teeth or lifelong photo identification records, and well-preserved tissue. However, they also included young adult and juvenile animals in the study too.

Upon imaging, the samples were examined with a microscope and photographed with a digital camera. The sections were scored subjectively by two researchers based on the amount of immunolabeling present:

0=no labeling





5=very large amount

Samples labeled for glial fibrillary pacific protein, or GFAP, and Ionized calcium-binding adaptor molecule, or IBA1, were imaged on a microscope with the imaged being got a software program designed to capture slide images from microscopes. In addition, the burdens were on another software with calculations of all percent areas of positive labeling. All the slides were imaged with an oil immersion objection on a microscope.

What did they find?

The results from this study found accumulations of amyloid-beta plaques and hyperphosphorylated tau in the samples collected from the remains of pilot whales, white-beaked dolphins, and bottlenose dolphins. Upon their deaths, the animals had shown signs of old age. What’s more interesting about this find is that the locations of the brain lesions found in these animals matched with areas that are seen in people with Alzheimer’s.

While it was impossible for the researchers to “detect” Alzheimer’s in animal remains, there’s no record of an increased level of both proteins in people who were Alzheimer’s-free.

How does it fit the existing theories of why cetaceans strand?

Because dolphins are social animals, some researchers believe they help care for struggling pod members whose cognitive levels are declining. As a result, caring for a struggling pod member may increase their chance of survival, but what if that pod member is their matriarch? If she suffers from a cognitive decline as she ages, she could suffer from a sudden onset of confusion over time, and place and poor detection of the geomagnetic field. Because of her disorientation, the matriarch accidentally leads her pod into shallow water, resulting in stranding.

What can we learn from the study?

While we have more to learn regarding the mystery of why cetaceans strand, it’s remarkably interesting to learn how pathological changes in animals can give us vital ideas about why they happen. While the deaths of the animals in question remain unknown, they can help support theories about how sick matriarchs are linked to mass animal strandings, because of their high social cohesion. In addition, it might help people learn more about how to care for loved ones who suffer from Alzheimer’s and other cognitive degenerative disorders.


Vacher, M. C., Durrant, C. S., Rose, J., Hall, A. J., Spires‐Jones, T. L., Gunn‐Moore, F., & Dagleish, M. P. (2022). Alzheimer's disease‐like neuropathology in three species of oceanic dolphin. European Journal of Neuroscience.

healthwild animalssciencefeature

About the Creator

Jenna Deedy

Zoo and Aquarium Professional, Educator, Cosplayer, Writer and B.A. in Psychology whose got a lot to share when it comes to animals, zoos, aquariums, conservation, and more.

Instagram: @jennacostadeedy

Reader insights

Be the first to share your insights about this piece.

How does it work?

Add your insights


There are no comments for this story

Be the first to respond and start the conversation.

Sign in to comment

    Find us on social media

    Miscellaneous links

    • Explore
    • Contact
    • Privacy Policy
    • Terms of Use
    • Support

    © 2023 Creatd, Inc. All Rights Reserved.