Living With a Pet Can Prevent Age-Related Cognitive Decline

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So, you are growing older and perhaps are beginning to worry about the possibility of the diminishing of your cognitive and mental abilities, which seems to be an inevitable result of aging. According to a recently published scientific report, you may be able to ward off such cognitive declines simply by getting a dog or a cat as a household companion.

Aging and Decreasing Mental Ability

Age takes a toll on all of us, both physically and mentally. It is well-established that as we age our cognitive faculties grow weaker, our memory is not as acute, and our verbal fluency and general mental processing abilities decline. This is not only important as a personal effect on our individual lives, but, since people are living longer, it is also becoming something of a worldwide crisis. It has been estimated that, globally, the number of people affected by dementia increased by 117 percent between 1990 and 2016, mainly due to the population's aging.

Unfortunately, no effective therapy is currently available to successfully reverse cognitive decline or to treat dementia. However, we are beginning to learn how certain lifestyle and social factors are associated with, and interact with, these age-related effects. One of these is loneliness.

The Loneliness Factor

Over the past few decades, the proportion of individuals living alone has increased. As of 2021, the proportion of single-person households in the United Kingdom reached 29.4 percent; in the United States, the proportion was 28.5 percent.

Some recent analyses have shown that older adults living alone are at higher risk of developing dementia, although the reason for this link between cognitive decline and loneliness is unknown.

Some other studies confirm that pet ownership (especially of dogs and cats) significantly reduces feelings of loneliness in individuals. So, does it make sense to link these two findings and suggest that, perhaps because it reduces loneliness, the ownership of a pet might also reduce age-related cognitive declines?

The ELSA Project

To test the hypothesis that pet ownership may be related to cognitive status in later life, you need a substantial sample of older individuals who have had their cognitive abilities tested over a number of years and whose living status (whether alone or with others, and with or without pets) is known. Fortunately, there is an ongoing project known as the English Longitudinal Study of Aging (ELSA), a continuing study designed to measure the status of people living in private households in England. It is a collaborative project run by University College London, the University of Manchester, and the University of East Anglia. Since its data collection began in 1998, it has measured more than 19,000 participants aged 50 years or older.

The methodology involves testing these older individuals every two years with questionnaires and nurse interviews. The nurse interview involves measurements of physical function and the collection of blood samples. The ongoing test group requires the addition of new participants as individuals already enrolled in the study become unavailable due to death or other factors.

Most importantly for our concerns, in 2010, some cognitive functioning tests were added to the nurse interviews, and a question about pet ownership was included in the general questionnaire.

For scientists, one of the most wonderful aspects of this project is that ELSA has made its data available to other researchers globally. This has resulted in more than 1,300 scientific publications from investigators around the world using this resource.

Loneliness, Pets, and Cognitive Status

Our current interest is in a recent publication by a group of researchers headed by Yanzhi Li, at the Department of Medical Statistics and Epidemiology at Sun Yat-sen University, Guangzhou, China. These scientists decided to see if pet ownership had any effects on the cognitive status of aging individuals. They chose a sample of individuals tested from 2010 to 2011 and compared it to a sample whose results were collected from 2018 to 2019. This gave them 7,945 individuals aged 50 and older who participated in both data collections.

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Two measures of cognitive ability were available. The first was a verbal memory task that had two components: an immediate and a delayed recall of a list of unrelated words and a verbal fluency task that required individuals to list as many animal names as possible within one minute. A composite verbal cognition score simply combined all of these measures.

First, the analysis of this data confirmed that individuals who live alone tend to show greater deterioration of their mental abilities. The lonely individuals (without pets) showed a greater decline in verbal memory and verbal fluency compared to those living with other persons in their household.

When we look at the effect of pet ownership, the results are quite startling. For individuals living alone, if they have a pet, the expected decline in their cognitive skills is significantly slowed. In fact, their scores look just like those of individuals living in households with other people. Those individuals who are living in multiple-person households don't show any particular benefit of pet ownership, presumably because living with other people already reduces their feelings of loneliness, and so the addition of a pet may not be needed.

This seems to suggest an interesting conclusion: Older adults living alone are at high risk for developing dementia and other forms of reduced cognitive abilities. Unfortunately, living alone is a state that is not easily changed. However, a simple and relatively inexpensive buffer against cognitive decline might be the addition of a pet dog or cat to the household.

How great is the effect? The authors of this report claim, "These findings preliminarily suggest that pet ownership might completely offset the association of living alone with faster rates of decline in verbal memory and verbal fluency among older adults."

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