- A new study measured the effects of petting a dog on human brain activity.
- Dogs have previously been shown to reduce stress, but the neurological mechanisms haven’t been studied.
- Many current and potential therapies incorporate the use of animals, especially dogs.
It’s long been said that dogs are “man’s best friend.”
Now, a new
Researchers recruited 19 healthy adults (9 women and 10 men) to have their brain activity measured over several sessions, both with and without being in the presence of a dog.
The researchers said the results could improve the effectiveness of animal-assisted therapies used to treat many conditions, including:
So how was the study performed? And what were the results?
Previous studies into the physiological effects that dogs have on humans often used imaging technology such as PET scans — no, not that type of pet but positron emission topography.
While imaging scans have a variety of medical uses, they do have some drawbacks in a study such as this one. They can be loud, and lengthy, and participants may need to remain still.
These are not characteristics that generally pair well with dogs, so previous studies frequently used pictures of dogs as stand-ins.
In this study, researchers opted to use functional near-infrared spectroscopy (fNIRS). Two electrodes were placed on participants’ foreheads to measure prefrontal cortex activity.
This area of the brain plays an important role in social cognitive processing.
Participants were measured first in a neutral state, facing a white wall. Then measurements were taken as contact with a dog was progressively introduced.
First, the participants could see the dog, then sit beside it, and finally pet it before returning to a neutral state. None of the participants had any dog allergies or phobias.
These measurements were taken across 6 sessions for each participant: 3 with a dog, and 3 with a plush animal. The plush held a hot water bottle within it to give it more weight and warmth.
Three actual dogs were used, all females ages 4 to 6. There was a Jack Russel, a goldendoodle, and a golden retriever.
The results showed that brain activity increased substantially through the progressive phases of the experiment and oxygenated hemoglobin remained elevated (indicating increased activity) even after the dog left.
The plush had similar effects but only at first. Researchers said that as participants returned for more sessions, the difference in brain activity between dog and plush sessions significantly increased.
This study found a novel application for fNIRS, but is it a good tool for the job?
Yes, it is, according to Dr. David A. Merrill, a psychiatrist and the director of the Pacific Neuroscience Institute’s Pacific Brain Health Center at Providence Saint John’s Health Center in California.
“fNIRS is valid. There are decades’ worth of study using the technique measuring brain activity. [It] affords a view into the brain based on blood oxygenation without the need for a big, immobile scanner,” Merrill told Healthline.
Jen Summers, PsyD, a utilization review specialist at Los Angeles-based Lightfully Behavioral Health, told Healthline she agreed the fNIRS is a valid measurement tool but noted other areas she would like to see explored in more detail.
As an example, Dr. Summers pointed out that Labradors are the most common dog breed for therapeutic visitation animals, but none were included in this study.
“The study participants were ‘healthy subjects,’ however, the study did not define ‘healthy.’ It would be curious for future research to determine if participants with known medical conditions (i.e. anemia, autoimmune diseases, or anyone with noted deficits in oxygenated hemoglobin) would have increased frontal brain activation compared to their baseline,” said Summers.
Putting these study results to work is of interest across the medical community.
Dr. Joey R. Gee, a neurologist with Providence Mission Hospital in Orange County, California, told Healthline that dog-assisted therapies are “valuable for many chronic disorders and may be employed in settings where ‘calming’ is needed, such as with children and in long-term care facilities.”
“Pets such as dogs can and should be considered as an important therapeutic option for patients of all ages going through any number of physical or mental health issues,” he said.
Experts noted that one interesting aspect of the study was the increased effect of multiple sessions with a dog.
“Exposure and experience foster familiarity. Psychology studies have consistently demonstrated how the mere exposure effect influences a familiarity preference: we prefer things we are familiar with versus those which are novel,” said Summers.
“This certainty and comfort are undoubtedly bidirectional such that not only do we respond more positively, the dog also tends to respond more positively to humans they are bonded to securely,” said Merrill.