Scientific Results: Characterizing dog cognitive aging using spontaneous problem-solving measures: development of a battery of tests from the Dog Aging Project

September 12, 2024 - 11 minutes read

Who worked on this research?

Dog Aging Project Team Members:
Stephanie H. Hargrave
Emily E. Bray
Stephanie McGrath
Breonna Kusick
Julie A. Moreno
Daniel E. L. Promislow
Silvan R. Urfer
Dog Aging Project Consortium
Evan L. MacLean

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Collaborating with:
Theadora A. Block, Naomi Chao, Martin Darvas, Laura E. L. C. Douglas, Janet Galante, Brenda S. Kennedy, Lorelei R. Switzer, Lily Tees, Mikayla Underwood Aguilar, Gene E. Alexander, David A. Raichlen

Where was it published?

GeroScience

What is this paper about?

We know that, in some ways, aspects of cognitive aging in dogs, such as Canine Cognitive Dysfunction, mirror those of dementia and neurodegenerative disease in humans. Late-stage symptoms of Alzheimer’s disease in humans are preceded by mild cognitive impairments, and the same may be true of Canine Cognitive Dysfunction. While dogs have been studied as a model for Alzheimer’s disease, cognitive aging in community-dwelling companion dogs, like those enrolled in the Dog Aging Project, is still understudied. We aimed to develop games they could play to teach us about how cognitive performance on a variety of tasks is affected by age.

Much of the existing scientific literature looking at cognitive aging in dogs involves procedures that require dogs to be extensively trained before data collection can begin. While such methods work well in some settings, they are not feasible for collecting cognitive aging data on large numbers of community-dwelling dogs like those in the Dog Aging Project. Thus, we designed our tasks to be “spontaneous,” meaning dogs can participate with no prior training (or they can learn all they need to successfully participate within a few minutes). Dogs in this study played a series of five games aimed at measuring memory, adaptability, impulsivity, and social interaction.

Two short-term spatial memory games (the Delayed Search and Two-Location tasks) required dogs to remember the location of hidden treats across delays of 0-40 seconds and when faced with distractions or to remember the location of two hidden treats at once. In the Spatial Reversal task, which measures adaptability, we taught dogs to access a treat from one side of a barrier but then required them to flexibly shift to a new behavior and “unlearn” their previous problem-solving method when we suddenly changed how they could access the food. To measure impulsivity in the Cylinder task, we taught dogs to access a treat from one side of an opaque container but then swapped it for a transparent container. Being able to see the food induces a desire to move directly towards it, but dogs can only access the treat by going to the side of the container, requiring them to override the desire to approach the food directly and instead use their previously learned strategy in the face of temptation. Finally, in a brief social interaction task, we measured how long dogs spent close to and looking at a person.

We found that older dogs scored lower on cognitive tasks, particularly those involving spatial memory after a time delay and flexibility in the spatial problem-solving task. They also spent less time in proximity to but more time gazing at a human during the social task. Additionally, although it is well-established that smaller dogs generally live longer than larger dogs and larger dogs experience accelerated physiological aging, we found that the relationship between age and task performance did not differ based on dog body size. This suggests that brain aging may be an exception to the general idea that larger dogs age more rapidly. In a second experiment, we showed that using these tasks in studies of canine cognitive dysfunction in a clinical setting is feasible. Although dogs clinically assessed as having moderate or severe cognitive dysfunction had lower scores on average, some dogs with cognitive dysfunction performed similarly to those without.

What do these results mean for me and my dog?

While this study was exploratory in nature, it helped to lay the groundwork for potential future work on factors protective against cognitive decline. It established a set of relatively rapidly-administered tests that could be used in intervention trials in the future, possibly in clinical settings. This paper only involves cross-sectional data, meaning each dog was only tested once, and the results are a “snapshot” of what cognitive aging looks like across many individuals. Therefore, the data in this study cannot yet indicate what trajectories of cognitive decline look like within individuals or factors that may contribute to or help alleviate age-related cognitive impairment in dogs. We are working on longitudinal testing to see how cognition of individuals changes over time and hope to explore potential risk and protective factors in the future.

This study found that cognitive aging does not seem to differ between different sizes of dogs, despite dog body size and lifespan being closely related. This means that potentially if you have a small dog, they may be more likely than large dogs to experience cognitive decline because they will likely live to the ages at which it occurs.

You and your dog can help us learn more about dog cognitive aging by participating in the 1-2-3 Treat and Treat Hide and Seek activities at home, which measure similar aspects of cognition to the spatial memory games used in this study!

The entire Dog Aging Project Pack is invited to play the 1-2-3 Treat activity each April and the Treat Hide and Seek activity each August. As our Pack members participate in the annual cognitive games tasks, we hope to collect data to further develop and validate these tools, leading to a better understanding of the causes and consequences of cognitive aging.

You can learn more about the signs of cognitive aging in dogs at our previous blog post, Understanding Behavioral Changes in Senior Dogs.

Where can I learn more?

Hargrave, S.H., Bray, E.E., McGrath, S. et al. Characterizing dog cognitive aging using spontaneous problem-solving measures: development of a battery of tests from the Dog Aging Project. GeroScience (2024). https://doi.org/10.1007/s11357-024-01278-x

Abstract

Companion dogs are a valuable model for aging research, including studies of cognitive decline and dementia. With advanced age, some dogs spontaneously develop cognitive impairments and neuropathology resembling features of Alzheimer’s disease. These processes have been studied extensively in laboratory beagles, but the cognitive assays used in that context—which rely on time-consuming operant procedures—are not easily scalable to large samples of community-dwelling companion dogs. We developed a battery of five short-form tasks targeting three aspects of cognition that are impaired in Alzheimer’s disease: spatial memory, executive functions, and social cognition. In Experiment 1, we tested a cross-sectional sample of dogs (N = 123) and estimated associations between age and task performance. Older dogs scored lower on measures of spatial learning, memory, and response flexibility, and spent less time near, but more time gazing at, the experimenter. We found no differences in associations between age and performance across dogs of different body masses, a proxy for expected lifespan. In Experiment 2, we demonstrated the feasibility of these measures in clinical settings (N = 35). Dogs meeting clinical criteria for moderate or severe cognitive impairment scored lower, on average, than dogs characterized as mildly impaired and healthy agers, although these distributions overlapped. However, few dogs in our study cohort met the criteria for moderate or severe impairment. The measures presented here show promise for deployment in large-scale longitudinal studies of companion dogs, such as the Dog Aging Project.

Tags: Scientific Results