Three species of cetaceans could also suffer from Alzheimer’s disease, explains a recent study. The researchers found markers of the disease in three dolphins found stranded on different beaches.
Until today, it was thought that only humans could be affected by the disease. Alzheimer’s disease which affects more than 55 million people worldwide. But a new study published in theEuropean Journal of Neuroscience contradicts this idea. Scottish researchers have indeed found indicators in three cetaceans of different species: a white-beaked dolphin, a bottlenose dolphin and a pilot whale. Other types of dementia had been found in different animals but never this one!
For their study, the scientists analyzed the brains of 22 marine mammals stranded on different beaches. Using immunohistochemistry, a technique for locating different proteins, they identified several brain abnormalities typical of Alzheimer’s disease : an accumulation “of amyloid-beta plaques, an intraneuronal accumulation of hyperphosphorylated tau, threads of neuropils and neuritic plaques”, describes the study. However, there is no indication that the symptoms experienced by the animals are the same as ours. For this, living specimens should be scrutinized in detail.
Alzheimer’s disease could explain the mass strandings
Several hypotheses try to explain why Alzheimer’s disease can develop in these different dolphins. One speculates that this is because they can live for a long time after they cease to reproduce, another puts it down to hypoxia associated with their foraging in deep waters. Indeed, the availability of oxygen is less there, leading to a decrease in the level of oxygen in the blood and then in the body tissues.
Although the cause remains to be determined, according to the researchers, the pathology could explain the mass strandings pods of dolphins in the shallow waters! This is the thesis of « sick leader », or “sick leader”: if the dolphin leading the group is in the wrong place, then the whole group suffers! And “In humans, early symptoms of cognitive decline associated with Alzheimer’s disease include confusion of time and place and a poor sense of direction,” concludes the study.