Man’s Health’s Best Friend
Numerous studies have shown that dogs — one of the earliest domesticated animals — can help lower blood pressure, ease the loneliness of the elderly in nursing homes, and help children overcome allergies.
Now there’s research suggesting the hormonal changes that occur when humans and dogs interact could help people cope with depression and certain stress-related disorders. Preliminary results from a study show that a few minutes of stroking our pet dog prompts a release of a number of “feel good” hormones in humans, including serotonin, prolactin and oxytocin.
In addition, petting our pooches results in decreased levels of the primary stress hormone cortisol, the adrenal chemical responsible for regulating appetite and cravings for carbohydrates.
“The notion that serotonin increased with their own dog is a very powerful thing. Could a dog help mediate serotonin levels in order to help depressed patients?” asks Dr. Rebecca Johnson, a nursing professor and associate director at the Center for Animal Wellness, Missouri University College of Veterinary Medicine.
Johnson’s study expanded on research conducted in 1999 by South African scientists who found that 15 minutes of quietly stroking a dog caused hormonal changes that were beneficial to both the dog and the human.
But the South African study was small, involving only 18 people and a few friendly dogs, and didn’t test for serotonin, the brain chemical strongly linked with depression. Increased levels of the neurotransmitter serotonin make us more mentally alert, improve sleep and can make us less sensitive to pain.
In the larger Missouri study, 50 dog owners and 50 non-dog owners over the age of 18 sat in a quiet room for 15 to 39 minutes with their own dog, a friendly but strange dog, and a robotic dog. The robotic dog was included because electronic pooches, such as Sony’s AIBO, are being studied as a possible resource for the elderly who can’t look after a live animal.
Each session involved calm stroking or petting. Researchers checked blood samples of both the humans and dogs at the beginning of each session and monitored their blood pressure every five minutes. The dogs’ blood pressure dropped as soon as they were petted. The humans’ blood pressure dropped by approximately 10 percent about 15 to 30 minutes after they began petting the animal, at which point blood was again drawn.
Johnson’s study found that serotonin levels increased when interacting with the human’s own dog, but not with the unfamiliar animal. And serotonin actually decreased when interacting with the robotic dog.
Dr. Alan Beck, director of the Center for the Human-Animal Bond at Purdue University, says the serotonin changes reveal the “mechanism” of how pets influence our health. “It shows that there is a physiological mechanism [to relaxing with a pet], that it really is comparable to other things we know cause relaxation, like eating chocolate.”
In other words, the warm feeling we get from our dogs and other pets isn’t just a learned behavior, Beck says, but something that’s hard-wired into humans.
It’s a theory that’s been gaining notable scientific support for some time:
In 1995, Erika Friedman at the University of Maryland Hospital conducted a study involving 392 people, which found that heart attack patients with dogs were eight times more likely to be alive a year later than people without dogs.
In 1999, Swedish researchers reported that children exposed to pets during the first year of life had fewer allergies and less asthma.
Recently, separate studies reported that walking a dog contributed to a person’s weight loss and that dog walking can be a catalyst for social interaction with other people, a benefit that can help improve our sense of well-being — or even help us meet a future spouse.
“Puppy love — it’s better than you think,” by Jane Weaver