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As in humans, canine cognitive function declines throughout a dog’s life. They have in fact become valuable models for understanding Alzheimer’s disease. But this dementia in dogs is difficult to identify. Recently, through a large national study of pet dogs participating in the Dog Aging Project, researchers revealed that dogs over the age of ten see their risk of developing dementia increase each year. They were able to more accurately characterize this canine cognitive decline and pathways to improvement, while creating a database for Alzheimer’s disease.
Neurodegenerative diseases associated with aging have become increasingly prevalent among the world’s aging population. According to the WHO, more than 55 million people are affected by Alzheimer’s disease or a related disease in the world. But the complex pathological pathways that lead to the development of this disease are not yet fully understood and can be difficult to study. live in the early stages of disease progression. While transgenic animal models have been widely used to study it, limitations have been identified which have prompted a shift to non-transgenic animal models, dogs.
Indeed, canine cognitive dysfunction has many similarities with Alzheimer’s disease, such as the deposition of amyloid β plaques. As in humans, canine cognitive function declines throughout a dog’s life. Clinical signs of this decline appear to be related to learning and memory deficits, loss of spatial awareness, impaired social interactions, and disturbed sleep patterns.
But it is difficult to identify it, since the many behavioral changes are considered a normal part of aging by the owner. Not to mention that other health issues can overshadow the onset of dementia, which is usually seen in dogs over the age of eight, but can occur in dogs as young as six.
Recently, a team of American researchers conducted a large study involving 15,019 dogs enrolled in the Dog Aging Project, an ongoing investigation into canine disease and aging. They identified the main factors associated with the risk of a dog developing the extreme case of canine cognitive dysfunction, similar to Alzheimer’s disease, as well as the key role of physical activity. Their work is published in the journal Scientific Reports.
An increased risk each year from 10 years
While previous studies have found a link between aging and canine cognitive decline, they have tended to be much narrower than this new study. As mentioned earlier, the researchers relied on data from the Dog Aging Project.
Founded in 2014 by Kate Creevy, Daniel Promislow and Matt Kaeberlein, this project collects information on tens of thousands of dogs across the United States as they age. Moreover, in 2021, they published an article providing some ideas for dogs to live longer. This study project, funded by the National Institute on Aging, is launched by Cornell University, the University of Washington and the University of Arizona, in order to study the potential links between Alzheimer’s disease and this canine dementia, and whether it is triggered by the same genetic and environmental factors.
Specifically, the authors asked pet dog owners to complete two surveys. One of them contained questions about the dogs, their state of health (age, sterilization) and their physical activity, in order to establish a reliable mathematical model. The second was used to assess the dogs’ cognitive function. Analyzing more than 15,000 dogs, the authors noted that only 1.4% of dogs in the study showed signs of the disease. However, for dogs over ten years old, each additional year of life increases the risk of developing dementia by 52%.
Not to mention that, among dogs of the same age, health condition, breed type and neutering status, the risks of dementia were 6.47 times higher in dogs that were not active compared to those that were very active. active, just like in humans. The authors point out that these observations may reflect a variety of biological mechanisms, including a reduction in pro-inflammatory cytokines in the brain, which otherwise contribute to neural damage and death, and an increase in neural plasticity.
They add : ” Although this may suggest that regular exercise may protect dogs against dementia, we cannot be sure of this type of conclusion. Dogs with dementia or showing early signs of dementia may be less likely to exercise “. Indeed, dogs with dementia can get lost in familiar places, find themselves in a dead end behind furniture. Their failing memory does not allow them to remember that they can simply step back, whereas they generally have an astonishing awareness of their body.
In addition, this study demonstrates that dogs with a history of neurological, ocular or auditory disorders also had a higher risk of developing cognitive dysfunction.
Future advances for Alzheimer’s disease and canine well-being
One of the advantages of using dogs to study Alzheimer’s disease is that the progression of canine cognitive decline occurs much faster than in humans, simply because dogs have a shorter lifespan. Jan Krumsiek, assistant professor of physiology and biophysics at Weill Cornell Medicine, who studies the metabolism of Alzheimer’s disease, explained in a press release introducing the Dog Aging Project program: There are certain diseases where in humans, you have to wait 5, 10, 20 years to really see something. Whereas in dogs it only takes a year or two “.
Dogs are also better animal models for studying Alzheimer’s disease than mice, which have traditionally been used but do not naturally develop a similar type of dementia, said study co-author Kaeberlein. He adds : ” Companion dogs live with their owners in the human environment, and that’s something we really can’t recreate in the lab. “.
These findings may initially help veterinarians better diagnose dementia in dogs and find treatments to reduce the risk. Taking anti-inflammatories would in particular relieve joint pain in order to keep aging dogs active longer. As there is a clear link between activity level and the development of canine cognitive decline, this simple gesture could reduce the risk.
Secondly, the data collected and analyzed on the dogs could serve as a basis for research into early diagnosis and treatment in humans suffering from Alzheimer’s disease.