Two new studies provide evidence that being a pet owner, especially if it is a dog, might lead to a lower risk of dementia and Alzheimer’s disease. Although the exact reasons for this are a bit unclear, having a dog or other pets in your life may have a long-term benefit.
As I like to do, this article will include some brief information on dementia and Alzheimer’s disease along with a review of the two studies on the effect of owning a dog or other pets on these diseases.
What is dementia and Alzheimer’s disease?
Before I proceed, it’s important to describe what we currently know about Alzheimer’s disease (AD). It is a chronic neurodegenerative disease that usually starts slowly and worsens over time. It accounts for 60-70% of dementia cases, even though the terms are sometimes used interchangeably. Alzheimer’s disease is a form of dementia. The other forms of dementia include Lewy body dementia, frontotemporal disorders, vascular dementia, and mixed dementia, which is a combination of two or more of the different forms of dementia.
Amyloid plaques (caused by amyloid beta, or Aβ), phosphorylated tau tangles (pTau), and neurofibrillary tangles are generally easily visible pathologies that can be observed by microscopic analysis of brain tissue from autopsies of those potentially afflicted by AD. These plaques and tangles seem to affect nerve functioning. Despite these observations, the precise pathophysiology, or development, of the disease is not known.
Since amyloid plaques are often identified in patients with Alzheimer’s disease, a large amount of research is focused on attacking those plaques as a way to reverse the effect on nerves which leads to AD.
The causes of AD are unknown (notice how much we do not know about this disease), although it is speculated that it is mostly genetically related, with a large number of genes that underlie this relationship.
And since we have no clear understanding of the etiology and pathophysiology of AD, there are no effective treatments available today for the disease, although there are some drugs that target the amyloid plaques but have not been shown to change the course or outcomes of AD.
There are a couple of medications that help manage some of the symptoms of the disease, but they are certainly not cures. There are several drugs at the very earliest stages of development that may hold out hope to treat the underlying disease.
One more thing that needs to be made clear. There are no biological tests for Alzheimer’s disease — usually, you can only find the amyloid plaques and other pathologies in post-mortem autopsies. Unfortunately. in the absence of an autopsy, clinical diagnoses of AD are “possible” or “probable”, based on other findings, such as memory tests and other methods.
In the United States, about 10.7% of seniors (≥65 years) currently have Alzheimer’s dementia, and the incidence of dementia and Alzheimer’s disease is expected to rise substantially in the coming decades due to population aging, making it imperative to identify modifiable risk factors that may help mitigate its impact. The economic burden of AD is expected to surpass $2.8 trillion by 2030.
Dementia and pet ownership
In a paper published on 1 December 2023 in JAMA Network Open, Ciyong Lu, Ph.D., Department of Medical Statistics and Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, China, and colleagues examined 7,945 people, 50 years or older, in the UK who were living alone or with partners and had a pet living with them. The study, unfortunately, did not provide information on what kind of pet each person had.
The researchers found that those individuals with a pet were found to have less decline in verbal memory and verbal fluency than those without one. Verbal memory and verbal fluency are early indicators of dementia and Alzheimer’s disease.
On the other hand, pet ownership did not have a comparable effect on study participants who lived with other people.
These results show that companionship, whether from other humans or from a pet such as a dog, reduces the rate of cognitive decline that can lead to dementia and Alzheimer’s disease.
To be fair, this study has a couple of deficiencies. First, it only used early indicators of dementia or Alzheimer’s disease rather than a definitive diagnosis which could come years after this study was conducted. And second, the study population was almost exclusively white, so there could be differences if other demographic groups were included.
Nevertheless, the authors concluded:
…pet ownership was associated with slower rates of decline in verbal memory, verbal fluency, and composite verbal cognition among older adults living alone, but not among those living with others, and pet ownership completely offset the associations between living alone and decline in verbal memory, verbal fluency, and composite verbal cognition. These findings suggest that pet ownership might be beneficial for verbal memory and verbal fluency among older adults living alone.
Dementia and dog ownership
In a paper published on 7 October 2023 in Preventative Medicine Reports, Yu Taniguchi, Research Team for Social Participation and Community Health, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan, and colleagues surveyed more than 11,000 people between the ages of 65 and 84. Participants were asked whether they owned cats, dogs, or had no pets; as well as which types of exercise they engaged in more than once per week, such as walking, running, yoga, swimming, and cycling. After four years, researchers reassessed participants’ health conditions, and whether or not they had developed any dementia symptoms.
Here are their key findings:
- They found that dog ownership reduces the risk of dementia by over 40% in individuals over the age of 65.
- Cat ownership showed no statistically significant decrease in the risk of dementia.
- Dog owners who also had regular exercise had a 63% reduction in risk of dementia.
It is possible that dog ownership meant an increase in the amount of regular exercise compared to cat ownership since there is some evidence that exercise itself reduces the risk of dementia. However, it is also hypothesized that having the companionship of a pet like a dog helps reduce cognitive decline.
Summary of dog and dementia risk research
These are two interesting studies that seem to indicate that having a pet, especially a dog, can reduce the risk of cognitive decline which leads to dementia or Alzheimer’s disease. Like a lot of these observational studies, they can only provide us with correlation, not causation. In other words, the pets themselves may not prevent cognitive decline but it is the activities that an individual may have with that pet that helps reduce the risk of dementia.
So having a dog as your companion can lead to more healthy activities that help reduce the risk of dementia. And you just thought your good doggy was just a joy to have as a friend.
Citations
- Li Y, Wang W, Zhu L, Yang L, Wu H, Zhang X, Guo L, Lu C. Pet Ownership, Living Alone, and Cognitive Decline Among Adults 50 Years and Older. JAMA Netw Open. 2023 Dec 1;6(12):e2349241. doi: 10.1001/jamanetworkopen.2023.49241. PMID: 38147332; PMCID: PMC10751597.
- Taniguchi Y, Seino S, Ikeuchi T, Hata T, Shinkai S, Kitamura A, Fujiwara Y. Protective effects of dog ownership against the onset of disabling dementia in older community-dwelling Japanese: A longitudinal study. Prev Med Rep. 2023 Oct 7;36:102465. doi: 10.1016/j.pmedr.2023.102465. PMID: 37860160; PMCID: PMC10583170.
Lifetime lover of science, especially biomedical research. Spent years in academics, business development, research, and traveling the world shilling for Big Pharma. I love sports, mostly college basketball and football, hockey, and baseball. I enjoy great food and intelligent conversation. And a delicious morning coffee!
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