February 23, 2022
Years spent caring for a dog or cat may help mitigate cognitive decline among older adults, new research suggests.
In a large study of Medicare beneficiaries, pet owners had slower cognitive decline over 6 years than their peers who did not care for a pet.
"Previous research has studied the impact of pets on overall health, mood, and quality of life; but to our knowledge, our study is the first to consider the effect of duration of pet ownership on cognitive health in older adults age 65 and older," lead author Jennifer W. Applebaum, sociology PhD candidate and NIH predoctoral fellow at University of Florida, Gainesville, told Medscape Medical News.
Although the study could not prove a cause-and-effect relationship, the findings do provide early evidence suggesting that long-term pet ownership may protect against cognitive decline, added senior author Tiffany J. Braley, MD, associate professor of neurology, University of Michigan, Ann Arbor.
This is "a necessary step to understanding how relationships with companion animals may contribute to brain health," Braley said.
The findings will be presented at the American Academy of Neurology (AAN) 2022 Annual Meeting in April.
Benefits to Long-Term OwnershipThe researchers examined associations between pet ownership and long-term cognitive outcomes among 1369 adults participating in the Health and Retirement Study (HRS), a nationally representative cohort of US adults age 50 and older.
They used cognitive assessments from 2010 to 2016 to create a composite score derived from immediate and delayed 10-noun free recall test, serial seven subtraction test, and a backwards count test with a composite score range of zero to 27. All participants had normal cognition at baseline.
More than half of participants (53%) owned pets and 32% were long-term pet owners, caring for the pet for 5 years or more.
Compared with nonpet owners, pet owners were less apt to have hypertension (44% vs 49%) but more apt to have depression (24% vs 14%). Pet owners also had higher socioeconomic status.
Over 6 years, cognitive scores declined at a slower rate among the pet owners, and particularly among the long-term pet owners.
Taking into account other factors known to affect cognitive function, long-term pet owners, on average, had a cognitive composite score that was 1.2 points higher across 6 years than nonpet owners.
The cognitive benefits associated with longer pet ownership were more prominent for Black adults, college-educated adults, and men.
Less Stress, More Movement?However, Braley cautioned that it is not possible to assign "clinical meaningfulness to these particular cognitive scores that are delivered through the HRS, at least not in a manner that maps back to a specific clinical test or prognosis."
She also noted that more research is needed to further explore the possible reasons why owning a pet might help protect the brain.
"If a causal pathway exists between sustained pet ownership and cognitive health, physical activity and chronic stress reduction could each be mechanisms for this relationship," she said.
"Physical activity, which is associated with dog ownership, may provide cognitive as well as physical health benefits. Prior research has also identified associations between interactions with companion animals and physiological measures of stress reduction, including reductions in cortisol levels and blood pressure, which in the long term could have an impact on cognitive health," Braley said.
Importantly, Applebaum added, "we do not recommend pet ownership as a therapeutic intervention. However, we do recommend that people who own pets be supported in keeping them, via public policy and community partnerships."
"An unwanted separation from a pet can be devastating for a bonded owner, and marginalized populations are most at-risk of these unwanted outcomes," Applebaum said.
She noted that options to help include regulating or abolishing pet fees on rental housing, particularly in low-income communities and communities of color; providing foster or boarding support for individuals who are unexpectedly unavailable to care for their pets because of a health crisis or other emergency; and free or low-cost veterinary care for low-income owners.
"Pet ownership should not be sought as a means to preserve cognitive health. However, if a causal relationship exists between pet ownership and cognitive health, such data would provide further support for the development of programs to support older adults who are interested in maintaining or initiating pet ownership," Braley added.
First Large-Scale StudyCommenting on the study for Medscape Medical News, Shaheen E. Lakhan, MD, PhD, a neurologist in Boston, Massachusetts, noted that this is one of the first large-scale association studies that links pet ownership and cognitive health.
"The study supports other lines of research that found mental and emotional health improvements with pets. It supports this larger narrative that caring for a pet actually improves brain health: behavioral, cognitive, emotional, and physical domains," said Lakhan, who was not involved with the research.
American Academy of Neurology (AAN) 2022 Annual Meeting. Abstract 671. To be presented April 2, 2022.