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Dementia is an umbrella term for memory and learning loss, deterioration in thinking, behavior and the ability to do everyday tasks | Photo credit: Pixabay
Key highlights
- It is generally believed that 5-8 percent of people over the age of 60 have dementia
- One of the molecular features of Alzheimer’s disease in humans is the deposition of a peptide in the brain
- The relationship between cognitive impairment and Ab42 incidence in an aging dog may reflect a similar trend to that in humans
Budapest: In a recent study, scientists find that cognitive dysfunction in dogs models several key aspects of human dementia, underscoring the suitability and usefulness of companion dogs as animal models for aging studies.
The study was published in the journal GeroScience.
According to the research, researchers recently found that when researchers measured an Alzheimer’s disease-associated peptide (Ab42) in the brains of companion dogs, higher frequencies were associated with increased cognitive decline.
Dementia is a collective term for memory and learning loss, deterioration in thinking, behavior and the ability to do everyday tasks. The likelihood of developing dementia increases with age: It is generally assumed that 5-8 percent of people over the age of 60 suffer from dementia.
The most common cause of dementia is Alzheimer’s disease, for which unfortunately there is no cure yet. A major limitation in Alzheimer’s research is the lack of usable animal models that spontaneously develop dementia without genetic engineering and also adequately reflect the genetic and environmental complexity of humans.
Assistance dogs have recently emerged as exciting new models for human aging because they share the human environment, are exposed to similar risk factors, age approximately ten times faster than humans, and a subset of dogs spontaneously develop canine dementia as they age.
“If an old dog exhibits decreased learning ability, increased anxiety, loss of normal sleep patterns, and wandering aimlessly, it may be struggling with cognitive dysfunction in dogs,” said Silvan Urfer, veterinarian and researcher at the University of Washington, the study’s lead author . “It can be reliably diagnosed with a validated questionnaire that assesses the dog’s cognitive function. Values of 50 points and more indicate a diagnosis of cognitive dysfunction.”
One of the molecular features of Alzheimer’s disease in humans is the deposition in the brain of a peptide called amyloid beta 42 (Ab42).
The canine Ab42 peptide is identical to the human form. “We were interested in whether Ab42 levels in the brains of companion dogs are related to cognitive function and age. In collaboration with Martin Darvas, our laboratory developed a new assay to detect Ab42 in primate and dog brains and in CSF measure don’t have enough samples available yet, “says Matt Kaeberlein, one of the founders of the Dog Aging Project.
Here Urfer and Kaeberlein turned to Eniko Kubinyi, who, together with Kalman Czeibert, veterinarian, and Sara Sandor, geneticist, at the Institute for Ethology, ELTE in Budapest, set up the Canine Brain and Tissue Bank.
“We have developed a unique pet body donation protocol for dogs who, in consultation with their veterinarians, volunteer their dog’s body for research after medically justified euthanasia,” said Kubinyi. The Hungarian researchers collect the deceased’s brain and cerebrospinal fluid along with thorough documentation of the dogs’ previous cognitive performance.
This system enabled the team to correlate the postmortem histological and molecular data with behavioral measurements. They found significant positive correlations between Ab42 and age in all three brain regions examined (prefrontal cortex, temporal cortex, hippocampus / entorhinal cortex), while Ab42 correlated negatively with age in the CSF. The ab42 frequency of the brain in all three brain regions was also correlated with the Canine Cognitive Dysfunction Scale Score.
The relationship between cognitive impairment and Ab42 frequency may reflect a similar trend in the aging dog as it does in humans. It is well known that Ab42 and other Alzheimer’s disease-related pathologies in the brain appear years or even decades before clinical symptoms appear.
Both the Dog Aging Project and the Senior Family Dog Project aim to use privately owned assistance dogs as models for aging and age-related diseases in humans. Assistance dogs living with their owners capture the genetic and ecological diversity that cannot be reproduced in laboratory animals.
To study aging in dogs, an important aspect is the availability of biosamples from various organs for research, which should also include clinical and demographic information for these animals.
Both the existing Canine Brain and Tissue Bank (CBTB) at ELTE and the Dog Aging Project Biobank at Cornell University are addressing this emerging need by enabling Citizen Scientist owners to donate their dog’s body at the time of its natural end . These resources will be useful for conducting larger studies in the future as more specimens become available.
The correlation between Ab42 in the dog’s brain and the cognitive scores supports the suitability of the companion dog as a model for Alzheimer’s disease. It also illustrates the usefulness of veterinary biobanking to provide researchers with biosamples for analysis.
In the future, dogs could be used to study interventions aimed at preventing or treating Alzheimer’s-like pathologies. Such research can also help extend the healthy lifespan of our pets.
