Neurodegenerative Diseases: What Can Be Learned from Toothed Whales?

Neurodegeneration involves a wide range of neuropathological alterations affecting the integrity, physiology, and architecture of neural cells. Many studies have demonstrated neurodegeneration in different animals. In the case of Alzheimer's disease (AD), spontaneous animal models should display two neurohistopathological hallmarks: the deposition of β-amyloid and the arrangement of neurofibrillary tangles. However, no natural animal models that fulfill these conditions have been reported and most research into AD has been performed using transgenic rodents. Recent studies have also demonstrated that toothed whales - homeothermic, long-lived, top predatory marine mammals - show neuropathological signs of AD-like pathology. The neuropathological hallmarks in these cetaceans could help to better understand their endangered health as well as neurodegenerative diseases in humans. This systematic review analyzes all the literature published to date on this trending topic and the proposed causes for neurodegeneration in these iconic marine mammals are approached in the context of One Health/Planetary Health and translational medicine.