Abstract
… It's a favourite quote of ours — courtesy of AT Holley (FGM's grandfather). ‘You know you are getting old when every new sensation is a symptom,’ is another favourite.
They seem to summarise the experiences of the ageing population, and apply not only to humans but to our pets as well. In the past 10 years, there has been a slow realisation that, with the increasing ageing population of humans and pets, the care of the elderly, and how this can be managed, is of paramount importance, not only from an individual patient perspective but also for social and economic reasons.
We are at the beginning of a new age for the research and treatment of neurodegenerative diseases. Many (hopefully) parallels can be drawn with the beginning of the war against cancer in the 1960s, when large amounts of funding were channelled into gaining an understanding of this group of diseases. At present, this is not the case for the neurodegenerative diseases, but the importance of these conditions is now recognised. Some of this recognition is down to the research community, which has started to ‘translate’ its fundamental research.
There are some notable parallels in age-related changes in the brains of cats and people — and also some important differences. Hopefully, collaborative ‘rontier research’ in this area will ultimately benefit us all
However, there is an understanding in both the human and the veterinary fields that there is still much to be done, from fundamental research into molecular mechanisms through to recognition of clinical presentations and the development of treatment options. It is obvious that the relevant communities can all learn from each other and share important findings: these range from understanding the fundamental electrical and biochemical changes that underlie what we term ‘emory’ through to determining what the actual causes of these cognitive-impairing diseases may be. In the case of Alzheimer's disease, for example, is it beta-amyloid, is it tau, is it both, or is it something else completely?
What has become apparent is that many of the basic concepts are still up for discussion and debate, and much of the lack of knowledge has stemmed from a lack of patient numbers. In animal studies, in particular those involving our pets, if the numbers of patients that have been recruited are added up, then for some species (like cats) we are not close to approaching the thousands, or even hundreds, but are still in the tens. However, there is a growing band of pioneering scientists, medical clinicians and veterinary surgeons who are realising that there is much to learn from what used to be called ‘comparative biology’, but which for a while had fallen out of favour. This has become ‘frontier research’, and has spawned from the lack of true models of these diseases. There is a real need for better animal models, in particular where human genes have not been introduced by heterologous expression systems. Ideally, we need naturally occurring models that arise in species exposed to similar environments and stresses as us (ie, our pets).
In a review by Gary Landsberg and colleagues in this issue of JFMS, we can see exactly where we are in recognising cognitive dysfunction syndrome (CDS) in cats. 1 The authors — world leaders in cognitive dysfunction in pets — highlight just how much, and at the same time how little, we know about this condition in our cats. They discuss what an important role CDS can play in the health and welfare of our older cats, and consider the difficulties in making the diagnosis, particularly when concurrent and interacting conditions are so often present. The article considers the similarities and differences between ageing changes in the brains of cats and dogs and humans. It shows that that while CDS in our pets is certainly a reasonable naturally occurring model of Alzheimer's disease in humans (and vice versa), there are some important differences that need to be investigated and understood.
The authors also discuss developments in cognitive testing of cats, a science that is still in its infancy but is already generating fascinating findings. This is exciting research and very much in line with human medicine where there are moves to develop new ‘memory’ testing methods that include both spatial awareness and also changes in episodic memory.
The article concludes with a discussion of potential treatment options. As the authors state, there are currently only five medicines that have been approved for use in human dementia and it may take some time before we have a clinically proven arsenal of drugs for use in cats.
Ultimately, it is by working together that the research scientists, medical clinicians and veterinary surgeons can gain a better understanding of the naturally occurring comparative biology of neurodegenerative diseases in us and our pets. In doing this, breakthroughs gained in one species can be developed and advanced in other species, and we can move this important field of study forward at a greater pace that benefits us all.