Dogs could help us regulate our stress much better than we thought, according to a study

In a 2022 survey of 3,000 U.S. adults, more than a third of respondents reported feeling “completely overwhelmed” by stress most of the time. Meanwhile, a growing body of research documents the negative health consequences of high stress , including increased rates of cancer, heart disease, autoimmune conditions, and even dementia .

As people's daily lives are unlikely to become less stressful anytime soon, simple and effective ways to mitigate its effects are needed.

This is where dogs can help.

As researchers at the Institute for Human-Animal Connection at the University of Denver in the United States, we study the effects of pets on their owners.

Dozens of studies conducted over the past 40 years have confirmed that companion dogs help humans feel more relaxed . This may explain the growing phenomenon of people relying on emotional support dogs to help them manage their daily lives. It has also been shown that dog owners have a 24% lower risk of death and are four times more likely to survive for at least a year after a heart attack.

Also read : Our relationships with our pets reveal a lot about us. Mental health professionals should take note.

Along with a team of colleagues, we have just conducted a new study that suggests dogs may have a more profound and biologically complex effect on humans than scientists previously thought. And this complexity could have profound implications for human health.

The human stress response is a set of diverse, finely tuned, and coordinated physiological processes. Previous studies of the effects of dogs on human stress focused on a single process at a time. For our study, we expanded our focus and measured several biological indicators of body condition , also known as biomarkers , from the body's two main stress mechanisms. This allowed us to gain a more complete picture of how the presence of a dog affects stress in the human body.

The stress pathways we measured are called the hypothalamic-pituitary- adrenal (HPA) axis and the sympathoadreno-medullary (SAM) axis .

When a person experiences a stressful event, the SAM axis reacts quickly, triggering a "fight or flight" response that includes a surge of adrenaline and results in a surge of energy that helps cope with threats. This response can be measured using an enzyme called alpha-amylase .

At the same time, but somewhat more slowly, the HPA axis activates the adrenal glands to produce the hormone cortisol . This can help a person cope with threats that last for several hours or even days. If all goes well, when the danger is over, both axes stabilize and the body returns to normal.

Although stress can be an unpleasant sensation, it played an important role in the survival of the human species. Our hunter-gatherer ancestors had to respond effectively to acutely stressful situations such as an animal attack. In these cases, an overreaction could be as ineffective as an underreaction. Staying within the optimal stress response zone maximized human survival.

More complex information

After being released by the adrenal glands, cortisol is found in saliva, making it a readily available biomarker for monitoring reactions . This is why most research on dogs and stress has focused solely on salivary cortisol.

For example, several studies have shown that people exposed to a stressful situation have a lower cortisol response when they are in the company of a dog than when they are alone – or even lower than when they are in the presence of a friend.

Although these studies have shown that having a dog nearby can reduce cortisol levels during a stressful event, suggesting that the person is calmer, we suspected this was only part of the story.

What our study measured

For our study, we recruited approximately 40 dog owners to participate in a 15-minute, gold-standard laboratory stress test . This test involves public speaking and performing mathematical calculations aloud in front of a panel of emotionless individuals posing as behavioral scientists.

Participants were randomly assigned to two groups: those who brought their dogs to the lab and those who left their dogs at home. We measured cortisol levels in blood samples taken before, immediately after, and approximately 45 minutes after the test as a biomarker of HPA axis activity. And unlike previous studies, we also measured the level of the enzyme alpha-amylase in these same blood samples as a biomarker of SAM axis activity.

As expected, consistent with previous studies, people with their dogs experienced lower cortisol spikes. But we also found that those with their dogs experienced a significant spike in alpha-amylase, while those without their dogs had virtually no response.

The lack of response may seem positive. But in reality, a zero alpha-amylase response may be a sign of a dysregulated stress response . This is often seen in people suffering from severe stress reactions, chronic stress, or even post-traumatic stress disorder. This lack of response is caused by chronic or severe stress, which can alter how our nervous system reacts to stressors.

Also read : Finally recognize complex post-traumatic stress disorder, to better treat it

In contrast, participants with their dogs showed a more balanced response: their cortisol levels didn't rise too much, but their alpha-amylase was still activated. This shows that they remained alert and focused throughout the test, and then were able to return to a normal state in less than 45 minutes. This is the ideal amount of time to effectively manage stress. Our research suggests that our canine companions help us stay in a healthy stress response zone.

Dogs and Human Health

This deeper understanding of the biological effects of dogs on human stress responses opens up exciting possibilities. Based on the results of our study, our team has launched new research that uses thousands of biomarkers to further our understanding of the biology behind how psychiatric service dogs reduce post-traumatic stress disorder in veterans.

Also read : Trauma in war zones: the impact of extreme situations on the psyche

But one thing is already clear: dogs aren't just good companions. They may well be one of the most accessible and effective tools for staying healthy in a stressful world.