A new study suggests that owning a dog at home significantly improves adolescents’ mental health. Scientists hypothesize that this positive effect may be partly due to the sharing of microbes between the dog and the adolescent.
Professor Takefumi Kikusui of Azabu University in Japan, who led the study, states that interacting with dogs reduces stress and stimulates the release of oxytocin, the attachment hormone. However, his team’s research also revealed other potential reasons.
“Several studies have confirmed the mental health benefits of dog ownership, and we showed that the microbiome might be one of those mechanisms,” noted Kikusui.
As part of the paper published in the journal iScience, Kikusui and his colleagues analyzed the results of a survey of 343 mentally and physically healthy adolescents participating in an adolescent cohort study. Of these, 96 were dog owners.
The study found that 13-year-old adolescents who owned a dog showed significantly lower scores at age 14 for problems such as: social isolation, thought problems, delinquent behavior, and aggressive behavior.
The researchers analyzed the microbes present in the adolescents’ saliva. They found that 12 types of bacteria, including Streptococcus and Prevotella, were present in significantly smaller amounts in the saliva of adolescents who did not own dogs.
The scientific team transferred microbes from the saliva of these adolescents to germ-free mice (mice without their own microbes). As a result, mice with the microbiome of dog-owning adolescents:
-
Sniffed unfamiliar mice with greater interest.
-
Approached cagemates caught in a trap more frequently.
“This latter behavior is called ’empathic concern,’ which is a type of empathetic response in humans and animals,” explained Professor Kikusui.
While direct comparison of human and mouse behavior is impossible, scientists suggest that the results indicate the microbiota is partially responsible for the improvement in the adolescents’ social behavior.
The study did not analyze the microbes of the dogs themselves. Kikusui said it is unclear whether these microbial differences stem directly from the dogs or whether dog ownership reduced stress, which in turn caused the changes in the microbiota.
Professor Kikusui adds that this study does not mean everyone should own a dog.
“Even without owning a dog, maintaining a diverse microbiome can potentially improve mental health scores,” he stated.
Furthermore, a dog with problematic behavior may even cause stress to the owner, so dog ownership will not be a positive experience for everyone.
