In a recent study published in the journal JAMA Network Open, researchers investigated the association between pet ownership and cognitive decline in the elderly. Analyses of more than 7,900 adults above the age of 50 years revealed that pet ownership, while insignificant in adults living with others, significantly alleviated verbal cognitive declines in adults living alone.
Study: Is pet ownership associated with cognitive decline in older adults, and how does pet ownership mitigate the association between living alone and the rate of cognitive decline? Image Credit: Agnes Kantaruk/Shutterstock.com
This research suggests that owning a pet can slow verbal memory, cognition, and fluency aging in the elderly living in solitude and forms the basis for future research into the benefits of pet ownership in aging adults.
Can we fight cognitive aging? Can our furry friends help?
Growing old is often associated with stark declines in memory and cognition and has been found to significantly correlate with an increased risk of neurodegenerative disorders such as dementia. Modern medicine has substantially increased humanity's average life expectancy, but evolutionary theory dictates that natural selection is blind to fitness reductions temporally following reproductive age.
The aforementioned medical advances, in tandem with poor life- and health behavioral choices, have resulted in an alarming surge of neurodegenerative disorder prevalence. Estimates predict an almost 3-fold growth in the number of dementia patients in 2050 (153 million) compared to today's prevalence (57 million), exposing patients, caregivers, and national healthcare systems to significant financial and psychological stress.
Unfortunately, there is currently no effective therapy to reverse the effects of cognitive or neurodegenerative disorders, making interventions aimed at identifying high-risk populations and slowing these natural reductions the best hope that current and future patients have. Studies aimed at exploring the benefits of modifiable risk factors may elucidate the best steps for healthy aging.
Recent research has explored the associations between routine isolation and cognitive decline and has highlighted two concerning trends – firstly, today's fast-paced, mobile lifestyles and the increased subscription of families to the nuclear family structure (parents living with their children until the children reach adulthood, at which points they leave their 'nest' to establish their own nuclear families) has drastically increased the number of single-person households. The United States of America (US) and the United Kingdom (UK) are estimated to have 28.5% and 29.4% of all their elderly citizens living alone, respectively.
Secondly, cognitive research has revealed that aged adults living alone are at substantially higher risk of neurodegenerative decline and dementia development (9%) than those living with family.
Loneliness has been underscored as the primary culprit in these observations, with some authors suggesting pet ownership as a potential intervention to alleviate these risks. While some cross-sectional studies have aimed to unravel the associations between pet ownership and neurodegeneration, their results remain confounding.
Establishing the benefits of owning a furry friend (or several pets) would present a relatively cost-effective long-term solution to promote healthy aging among the growing population of lonely elderly.
About the study
In the present study, researchers utilized the cohort-based approach to elucidate pet ownership's cognitive pros and cons among aged English adults. The study follows the recommendations of the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guidelines.
The sample population was derived from the English Longitudinal Study of Ageing (ELSA), a UK-wide, long-term database of community-dwelling adults over 50. ELSA was established in March 2002, with participants biennially followed up in 'waves' through July 2019 (wave 9). Data collection on pet ownership was included as a follow-up requirement during wave 5 (June 2010), thereby making wave 5 the baseline for this study. Of the 10,095 English adults included during wave 5, 7,945 participants provided informed written consent and were included in the current study dataset.
Community versus alone living was defined as the participant living with any other human (former) as opposed to the participant's household comprising only the participant (latter). Participants' cognitive function was assessed using the immediate and delayed recall of 10 unrelated words (verbal memory) and the fluent listing of common animal names (verbal fluency). Demographic characteristics, specifically race/ethnicity (White versus others), were used as covariates during statistical analyses.
Analyses comprised independent 2-sample t tests, and Pearson χ2 tests with variables listed as mean and standard deviation (SD) for continuous variables, and frequencies for categorical variables. Linear mixed models were used to evaluate the independent and combined effects of living alone and pet ownership on cognitive decline across measured waves (5 through 9).
Study findings
Of the 7,945 participants included in the study, 56% (4,446) were women, and 97.5% (7,746) were White. More than 35% of participants (2,791) were pet owners, and almost 27% (2,139) lived alone. Cognitive analyses revealed that pet owners displayed significantly reduced rates of cognitive decline compared to participants living alone without pets. Composite verbal cognition (β coefficient = 0.008), verbal memory (β coefficient = 0.006), and verbal fluency (β coefficient = 0.007) all showed improvements in the presence of pets.
Analyses revealed that living alone resulted in a significantly increased risk of cognitive decline and dementia onset, making it the most significant modifiable risk factor across verbal cognition, memory, and fluency. Notably, no statistically significant improvements were noted in participants who did not own pets but lived with others. This suggests that pet ownership alleviates the loneliness-induced cognitive demerits of living in isolation.
"…compared with individuals living with others those living alone showed a faster decline in composite verbal cognition (β coefficient, −0.021 [95% CI, −0.027 to −0.014] SD/y), verbal memory (β coefficient, −0.018 [95% CI, −0.025 to −0.011] SD/y), and verbal fluency (β coefficient, −0.015 [95% CI, −0.022 to −0.008] SD/y)."
Conclusions
The present study highlights the cognitive demerits of living in isolation during old age – individuals above the age of 50 are at significantly higher risk of mental and neurodegenerative decline than those living with others. From previous research, loneliness is the most probable reason for these observations.
Encouragingly, pet ownership was found to completely alleviate the demerits of living alone, resulting in improved decline rates comparable to individuals living with family.
The study was unable to find synergistic benefits to living in human and pet company, with no additional improvements recorded when combining these interventions. This suggests that the benefits of pet ownership are greatest in individuals living alone.
Renaissance of "food as medicine" in modern clinical trials