Alzheimer's disease has long been known to afflict older humans, but it appears that the age-related neurological disorder also affects animals.
Markers Of Alzheimer's Disease In Animals
In August this year, Kent State University researchers detected traces of the disease in the brain of chimps that died from natural causes at research centers and zoos. Now, researchers of a new study have reported finding signs of Alzheimer's disease in dolphins, marking the first time the condition has been detected in a wild animal.
In the new study, which was published in Alzheimer's Disease & Dementia, researchers reported finding protein plaques and tangles, which are considered key markers of Alzheimer's in dolphins.
Researchers found plagues of the beta amyloid protein and tangles of the protein tau in the brains of the marine animals. In humans, these proteins are smoking guns of Alzheimer's disease.
Beta amyloid that lingers in the brain results in the formation of plaques between neurons. The tau, on the other hand, forms tangles that destabilize the neurons. These neurological disruptions together produce dementia.
Not A Human-Specific Disease
The study offers additional evidence that Alzheimer's disease, the most prevalent form of dementia among humans, is not a human-specific disease.
"It is very rare to find signs of full-blown Alzheimer's Disease in non-human brains," said Simon Lovestone, from Oxford Health NHS Foundation Trust. "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."
The findings mean it is possible to use other animals to study the condition. Unlike most animals that die shortly after the end of their fertile years, orca whales and dolphins tend to live past their reproductive years just like humans. Researchers have long wondered if dolphins can also be susceptible to age-related diseases as a result of their long lives, so they looked at the brains of dead dolphins from the wild whose bodies were washed ashore after their death.
"We present novel evidence that Dolphin, like man, an animal with exceptional longevity, might be one of the very few natural models of Alzheimer's disease," the researchers wrote in their study.
Symptoms Of Alzheimer's Disease
Early warning signs of Alzheimer's in humans include speech problems, decline in sense of smell, hearing loss, and need for extra sleep at night. It is not clear though how dolphins are affected by their version of Alzheimer's disease, or if they suffer from any memory loss that characterizes the condition in humans.