Do Pets Really Help Aging People Stay Mentally Sharp?

Source: Image by Hal Herzog

(Note: Several months after this post was written, a new study published in the Journal of the American Medical Association found that pet ownership was associated with slower cognitive decline in older people who lived alone. There was no effect of pet ownership on the mental status of people not living alone. You can read the full report here.)

You have probably seen TV ads in which an older man or woman looks into the camera and swears that a daily dose of Prevagen, a dietary supplement, has made it easier for them to remember things. Don’t believe it. No solid research supports these claims. Indeed, the Attorney General of New York called the Prevagen marketing campaign a “clear-cut fraud.”

A Pet Effect on Cognition in Older People?

But is it possible that living with pets can keep people sharper as they age? The idea is not far-fetched. Research on the impact of companion animals on human mental and physical health has produced mixed results. However, some studies have found that pets can reduce stress in their owners, facilitate social interactions, increase physical activity, and stimulate the secretion of hormones like oxytocin.

Based on these results, five studies have recently been published in peer-reviewed scientific journals on the relationship between pet keeping and cognitive decline. The studies were similar. They were all:

• longitudinal investigations of age-related changes in mental abilities in pet owners and non-owners
• based on data from preexisting epidemiological studies of the impact of aging on mental and physical health
• attempted to control for “covariates”—non-pet factors that could account for differences in cognition such as gender, age, income, and chronic health conditions
• correlational studies rather than clinical trials. They could find statistical associations between pet ownership and cognitive abilities but not prove that differences were caused by living with a pet

The Studies

Here are summaries of the studies listed by publication dates.

Study 1. Elderly dog owners were worse off than non-owners.

Published in 2019, the first study to examine the relationship between pet ownership and cognitive changes in older people was conducted by an international team of researchers headed by Nicola Veronese. They used data from over 8,000 adults participating in the English Longitudinal Study of Aging to examine changes in memory and verbal fluency over six years in dog, cat, and non-pet owners.

After six years, the memory scores of dog owners had declined more rapidly than the scores of non-pet owners. The cat owners, however, fared better—indeed, they had smaller declines in verbal fluency than non-pet owners. (See full text).

Study 2. Pet caretaking had no impact on the likelihood of dementia.

Sandra Branson and Stanley Cron examined whether pet caretaking reduces a decline in cognitive abilities over 12 years. Their results were published in 2022 in the journal Anthrozoos. The subjects were 673 pet caretakers and 1,578 individuals without pets participating in the Health and Retirement Study—a longitudinal study of a large and racially diverse sample of Americans over the age of 50. Changes in mental sharpness were assessed using composite scores on the Telephone Interview for Cognitive Status Test (TICSm).

Once factors such as gender, age, education, ethnicity, and exercise were taken into account, the researchers found no differences in the risks of mild cognitive impairment or dementia in pet caretakers and people who did not have a pet.

Study 3 – Some older pet owners were mentally sharper (in some ways).

Jennifer Applebaum from the University of Florida and her colleague also analyzed pre-existing data from the Health and Retirement Study. They examined changes in cognitive abilities in 1,369 pet owners and non-owners in the 2012 and 2016 waves who were given the TICSm telephone interview assessment. Unlike Branson and Cron, they divided pet owners into two groups—longer-term pet owners (more than five years) and short-term pet owners.

Animal Behavior Essential Reads

Orangutan Treats His Wound with a Medicinal Plant

The Emotional Lives of Animals and Why They Matter

As reported in the Journal of Aging and Health, the researchers found the benefits of pet ownership accrued to a subgroup of participants—individuals older than 65 who had their pets for more than five years. They showed less decline in their cognitive scores when compared to non-owners. This difference was attributed to their better performance on verbal recall and memory. (The differences in the scores were “statistically significant,” but their clinical relevance is unclear.) Having a pet did not benefit participants 65 or younger or individuals who had pets for less than five years.

Study 4. Japanese dog owners were much less likely to suffer from dementia

In a 2023 study, Japanese researchers examined the onset of dementia among 11,194 elderly residents participating in the Ota Genki Senior Project. (Ota is a township in Tokyo.)

The results were impressive. Four years after they were initially assessed, current dog owners were 40 percent less likely to be suffering from dementia than people who did not have a dog. Unfortunately, having a cat had no impact on rates of dementia. However, pet ownership is not common in Japan—only 9 percent of the participants had a dog and 6 percent lived with a cat.

Study 5 – Pets and dog-walking contributed to better mental functioning.

The most recent study was published by a research team headed by Erika Friedmann and Nancy Gee. It appeared in the journal Scientific Reports. Their analyses were based on 637 dog, cat, and non-pet-owning adults participating in the Baltimore Longitudinal Study of Aging. As a group, the subjects were highly educated, married, and economically well-off. And when they were first tested, they were in good health, with no cognitive impairments. The participants were assessed every one to four years on 11 cognitive measures.

After adjusting for age, and a variety of chronic health conditions, dog owners showed lower rates of cognitive decline than non-owners on six of the measures and cat owners on four of them. Further, dog owners who walked their dogs fared better than owners who did not. The researchers concluded, "We provide important longitudinal evidence that pet ownership and dog walking contribute to maintaining cognitive function with aging.”

The Good News and the Bad News

As the social psychologist David Pizarro warned on the delightful podcast Psych, “You can never trust the results of a single study.” His point is illustrated by differences in the findings of the studies on the effect of pets on cognition as people age.

One study found no impact of pets on the mental abilities of older people, three found pet owners were at least somewhat better off, and one study reported dog owners (but not cat owners) fared worse than people without a companion animal. (As is usually the case, only the studies that found positive impacts of pets on cognition in older people attracted the attention of the media.)

First the good news: The results of three of the five studies were encouraging. The bad news is that two studies found no “pet effect” on cognitive decline.

The Causal Arrow Problem

Then there is the pesky “causal arrow” problem. The pet owners in these studies tended to be younger, more educated, wealthier, more physically active, and in better health. Does living with pets cause improved cognition or are mentally intact older people simply more able to care for companion animals?

I know that my parents' dogs, a series of feisty dachshunds all named Willie, brought them great joy as they got older. However, the jury is still out on whether pets ameliorate the ravages of old age on their owners' mental abilities. But I am sure the evidence that pets help delay memory loss is a lot better than the empirical evidence for the effectiveness of Prevagen.