Blog – Do Cats, Dogs and Dolphins Get Dementia Too?

It is a fact that most of our understanding about neuroscience and how the brain works is based not on studying humans but on other animals. How a nerve cell works came from studies on animals such as squid, sea anemones, cockroaches, even crabs. From these fundamental studies came the understanding of action potentials and even how simple nerve circuits work, specifically how nerve cells talk to each other.

And of course, how nerve cells talk to each other leads to the fundamental question of “What is a memory?” This question will be answered in lots of different ways (usually dependent on the type of scientist you are talking to), but the fact remains we still don’t really know. Somehow the physical connection at that synapse can hold information in a form that we interpret as a memory.

Fast forward and of course scientists started to use more complex animals from birds, rodents and other mammalian species. Then in the latter part of the 20^th Century, as technologies advanced exponentially, we started to look directly at human material. Indeed, to paraphrase the Nobel Prize Winner, Sydney Brenner who used a type of worm in his neuroscience, he predicted that the animal model for the 21^st Century was called Man.

Part of me feels that we have forgotten our comparative physiology and pathology roots and certainly when I first started working on dementia there was an unwritten central dogma that only humans could suffer dementia. Well, that turns out to be totally untrue. My own interest in spontaneous models of non-human dementia came from an observation at home one Saturday morning. “Cardhu”, one of my favourite cats, was become increasingly odd in his behaviour: forgetting where his food was, confusion of where he was in the flat, made banshee noises at night; and unfortunately, also forgetting where the litter tray was! In talking to my wife Danielle who happens to be a world specialist on cats (and was recently awarded an OBE for services to Feline Medicine), I asked her: Do cats get dementia?  “Cognitive Dysfunction Syndrome” was the term used in Veterinary circles, but it led to Danielle and I looking for the pathology signs of dementia (specifically Alzheimer’s disease amyloid plaques and modified tau) in cats who had died with neurological problems. Fast forward, we saw tau pathology and an odd looking amyloid deposition. We were not alone others had looked at dogs where the amyloid deposition looked like human form, but the tau looked normal.

Some years later I went to talk by Sir Simon Lovestone entitled: Diabetes, Dementia and the Killer Whale. In this lecture, Simon was proposing that other animals that live a long time but stop reproduction quite early (like humans), might also display signs of dementia. This sparked a memory because after Danielle and I had published our cat work, a PhD student from Spain contacted me saying that they had a small bit of data on dolphins (from strandings), but didn’t know what to do with it. Cue a publication with all of us on Alzheimer’s disease in humans and other animals: A consequence of postreproductive life span and longevity rather than aging ¹. This was further continued by then a chance meeting in a pub with someone I hadn’t seen in ~30 years. Mark Dalgleish was a veterinary pathologist who routinely took samples from cetacean strandings around Scotland. Cue work carried out then showed that three different species of dolphins around Scotland showed similar pathological signs as we see in humans ² which led in both cases to many media interviews.

When you start to look more closely, it turns out that our fellow animals also have the capability of getting dementia.

Indeed, recently from the work of a talented final year undergraduate project student, we have published a summary of domestic animals, farm animals and sea mammals ³. Now, I stress I am not advocating the use of any of these animals for testing of new compounds, heavens know show much lecanemab and/or donanemab you would need for a whale! But it is the fact that we are not unique and other species, if they live long enough, can show signs of developing a dementia.

Personally, I think a more interesting question can be asked of why do some animals don’t get dementia? In the same way we have found the blind mole rat seems to be immune to cancer, why are some animals, which live a long time, appear to be immune to dementia?

So what for the future? Well the US is about to embark on stopping all animal research, which of course has underpinned human disease research; how this will impact in Europe no one quite knows, but it is based on the premise that we can take human skin cells and make them into nerve cells and then mini-organoid brains. We also can produce enormous amount of human data very quickly, though we still have a fundamental issue that we can’t take biopsies of the human living brain, and so we look for proxies in other bodily fluids.

This is all great, but we must remember that humans are not the only species that can get dementia and we can both benefit. As my wife Danielle says human studies have been fantastic at informing her how to treat her cats…

Professor Frank Gunn-Moore

Author

Professor Frank Gunn-Moore is an academic and researcher in neurodegeneration and dementia research at the University of St Andrews, Scotland. His group has advanced understanding of the early cellular and biochemical mechanisms of Alzheimer’s disease, including links between mitochondrial and synaptic dysfunction, and has pioneered new models including the identification of Alzheimer’s-like pathology in cetaceans. His research has also identified potential therapeutic targets, novel signalling pathways such as FRMD6/Willin in the Hippo pathway, and contributed to patented optical technologies developed with industry. He has published over 150 research papers across biology, chemistry and physics, reflecting the interdisciplinary breadth of his work.

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