Alzheimer’s disease-like neuropathology in three species of oceanic dolphin Marissa C Vacher cs 2022 Eur.J.Neusrosci.
doi org/10.1111/ejn.15900 open access

AD is the most common neuro-degenerative disease, the primary cause of disability & dependency among elderly humans worldwide.
AD is thought to be a disease unique to Hs, although several other animals develop some aspects of AD-like pathology.
Odontocetes share traits with Hs that suggest they may be susceptible to AD.

The brains of 22 stranded odontocetes of 5 different spp were examined (immuno-histo-chemistry) to investigate neuro-pathological hallmarks of AD:
amyloid-beta plaques, phospho-tau accumulation, gliosis:
all aged animals accumulated amyloid plaque pathology,
in 3 animals of 3 different spp of odontocete, there was co-occurrence of amyloid-beta plaques, intra-neuronal accumulation of hyper-phosphorylated tau, neuropil threads & neuritic plaques.
1 animal showed well-developed neuropil threads, phospho-tau accumulation & neuritic plaques, but no amyloid plaques.
Microglia & astrocytes were present as expected in all brain samples examined, but we observed differences in cell morphology & nrs between individual animals.
The simultaneous occurrence of amyloid-beta plaques & hyper-phosphorylated tau pathology in odontocete brains shows:
these 3 spp develop AD-like neuro-pathology spontaneously.

The significance of this pathology with respect to the health & death of the animals remains to be determined,
but it may contribute to the cause(s) of unexplained live-stranding in some odontocete species,
it supports the ‘sick-leader’ theory, whereby healthy conspecifics in a pod mass strand, due to high social cohesion.

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