Scientific Results: Associations between physical activity and cognitive dysfunction in older companion dogs

Who worked on this research?

Where was it published?

GeroScience, the official journal of the American Aging Association (AGE)

What is this paper about?

We know that some dogs will experience Canine Cognitive Dysfunction as they age. This condition is similar to Alzheimer’s disease in our own species. In humans, physical activity is thought to be a modifiable risk factor. In other words, exercise is something that is theoretically within our control and can potentially reduce the risk of dementia. In this paper, we used Dog Aging Project data from over 11,000 companion dogs, aged 6 to 18 years, to take a first look at this relationship in dogs.

Specifically, we determined three measures of cognitive health using owner responses to the Cognitive Social and Learned Behavior Survey (CSLB): current severity of cognitive dysfunction, change in cognitive dysfunction over the previous six months, and whether or not a dog was above the clinical diagnostic threshold for Canine Cognitive Dysfunction. All three of these measures were related to age. Specifically, older dogs had higher (i.e., worse) scores.

We then used statistical models to analyze which exercise variables were associated with these cognitive outcomes. Our main predictor of interest was a physical activity score that incorporated owner-reported average activity level, intensity, and duration from the Health and Life Experience Survey (HLES). We also accounted for age and demographic variables, as well as lifestyle factors and medical conditions that we hypothesized would affect activity levels and brain health.

We found a strong association between physical activity and cognitive dysfunction: less physically active dogs showed higher levels of cognitive dysfunction.

What do these results mean for me and my dog?

While the current study represents an important first step in identifying a relationship between physical activity and cognitive function, it cannot determine causality. In other words, we can’t disentangle if physical activity protects against cognitive decline, or rather if as dogs decline cognitively, they become less physically active. And of course it could also be both. Thus, we see this work as just the beginning— more research is needed, and especially longitudinally. To this end, we are continuing to collect health and activity information on each dog in the pack every year through the Annual Follow-up Survey. Of course, physical activity is known to generally contribute to overall health in both dogs and humans. Getting out with your pups for walks, runs, and romps is always a good idea!

Where can I learn more?

Bray, E.E., Raichlen, D.A., Forsyth, K.K., Promislow, D.E.L., Alexander, G.E., MacLean, E.L., Dog Aging Project Consortium. 2022. Associations between physical activity and cognitive dysfunction in older companion dogs: results from the Dog Aging Project. GeroScience. DOI: 10.1007/s11357-022-00655-8

Abstract:

Canine cognitive dysfunction (CCD) is a form of dementia that shares many similarities with Alzheimer’s disease. Given that physical activity is believed to reduce risk of Alzheimer’s disease in humans, we explored the association between physical activity and cognitive health in a cohort of companion dogs, aged 6–18 years. We hypothesized that higher levels of physical activity would be associated with lower (i.e., better) scores on a cognitive dysfunction rating instrument and lower prevalence of dementia, and that this association would be robust when controlling for age, comorbidities, and other potential confounders. Our sample included 11,574 companion dogs enrolled through the Dog Aging Project, of whom 287 had scores over the clinical threshold for CCD. In this observational, cross-sectional study, we used owner-reported questionnaire data to quantify dog cognitive health (via a validated scale), physical activity levels, health conditions, training history, and dietary supplements. We fit regression models with measures of cognitive health as the outcome, and physical activity—with several important covariates—as predictors. We found a significant negative relationship between physical activity and current severity of cognitive dysfunction symptoms (estimate =  − 0.10, 95% CI: − 0.11 to − 0.08, p < 0.001), extent of symptom worsening over a 6-month interval (estimate =  − 0.07, 95% CI: − 0.09 to − 0.05, p < 0.001), and whether a dog reached a clinical level of CCD (odds ratio = 0.53, 95% CI: 0.45 to 0.63, p < 0.001). Physical activity was robustly associated with better cognitive outcomes in dogs. Our findings illustrate the value of companion dogs as a model for investigating relationships between physical activity and cognitive aging, including aspects of dementia that may have translational potential for Alzheimer’s disease. While the current study represents an important first step in identifying a relationship between physical activity and cognitive function, it cannot determine causality. Future studies are needed to rule out reverse causation by following the same dogs prospectively over time, and to evaluate causality by administering physical activity interventions.