Dolphins Can Get Alzheimer's Disease, Too

When President Ronald Reagan – who would later suffer from it himself – designated November as National Alzheimer’s Disease Awareness Month back in 1983, fewer than 2 million Americans had Alzheimer’s. In November 2017, that number has almost tripled, to nearly 5.4 million. That number could rise to 16 million by 2050.
While progress has been made in understanding this disease, there still is no cure. It’s the sixth leading cause of death in the United States, taking the lives of more people than breast cancer and prostate cancer combined. Chances are you know someone who has or had Alzheimer’s. I do – I lost my mom to this terrible disease.

Until recently, Alzheimer’s disease was thought to only affect humans, but for the first time ever, the sad discovery was recently made that dolphins can also get it.

A team of researchers found unambiguous signs of Alzheimer’s in the brains of dead dolphins that had washed up on the coast of Spain. (How unfortunate for those dolphins, but fortunate that none had to be killed to make this discovery.)  Just like the brains of humans with the disease, the dolphins’ brains contained “plaques” of the protein beta amyloid as well as tangles of tau, another protein.
“This is the first time anyone has found such clear evidence of the protein plaques and tangles associated with Alzheimer’s disease in the brain of a wild animal,” said one of the researchers, Simon Lovestone, a geriatrics psychiatrist from Oxford Health NHS Foundation Trust. The study was published in Alzheimer’s and Dementia, the journal of the Alzheimer’s Association.
Since the researchers are rightfully opposed to testing captive dolphins, they said it’s difficult to know if older dolphins in the wild experience the symptoms of Alzheimer’s that people do, such as confusion and paranoia.
Why do dolphins get Alzheimer’s disease? Unlike most wild animals — but just like humans — dolphins can live for many years after losing their ability to reproduce. The researchers are looking for a connection between this longevity and Alzheimer’s disease.
The researchers believe that humans and dolphins are susceptible to Alzheimer’s because of the changes in how insulin works. This hormone regulates the blood’s sugar levels and triggers what the researchers called the “complex chemical cascade” known as insulin signaling. Alterations in this signaling can cause diabetes in people and other mammals. Previous studies have found that extremely limiting the calorie intake in animals like mice and fruit flies will change insulin signaling, and it also almost tripled the animals’ lifespans.
“That has the effect of prolonging lifespan beyond the fertile years, but it also leaves us open to diabetes and Alzheimer’s disease,” Lovestone said. “Previous work shows that insulin resistance predicts the development of Alzheimer’s disease in people, and people with diabetes are more likely to develop Alzheimer’s.”

The researchers hope this discovery will help improve the way new drugs are tested for treating Alzheimer’s disease. Dolphins have often proven to be “guardian angels” by saving people in distress at sea. Now, thanks to this sad discovery, they could also save our lives by helping to find a cure for this disease.