Dolphins, known for their extreme intelligence, have been found to develop Alzheimer’s disease, according to a new study from Oxford University published in the journal Alzheimer’s & Dementia.
In the human brain, Alzheimer’s is evidenced by amyloid plaques (sticky, folded pieces of protein) and neurofibrillary tangles (twisted proteins). These signs were seen in the brains of dolphins who died in the wild and whose bodies washed up on the Spanish coast.
“It is very rare to find signs of full-blown Alzheimer’s Disease in non-human brains,” said Prof. Lovestone, a researcher within the Oxford University Department of Psychiatry who worked on the study.
While the study says that dolphins are the first wild animals with “unambiguous signs” of the disease, a study from August 2017 involving chimpanzees found that the primates have also shown similar evidence of the brain characteristics of Alzheimer’s. In both animals, rules against testing on captive creatures prevent current study of living dolphins or chimpanzees to see their behavior when researchers suspect they have Alzheimer’s.
Perhaps the reason so few wild animals have shown signs of Alzheimer’s, a companion article for the study says, is because they often die shortly after their fertility period is over. Dolphins can live 25 to 40 years or longer.
The team, which included scientists from England, Scotland and the University of Florida, also posits that changes in insulin signaling may play a role in triggering Alzheimer’s.
“That (insulin signaling) has the effect of prolonging lifespan beyond the fertile years, but it also leaves us open to diabetes and Alzheimer’s Disease,” said Lovestone.
Scientists hope to continue to analyze dolphin brains to further understand how Alzheimer’s develops and ways it can be treated and prevented.