Family dogs may boost mental health and empathy by influencing human microbiomes

New research has found that family dogs may have a positive impact on mental health by changing people’s microbiomes.

“Raising dogs has beneficial effects, especially for adolescents, and these effects may be mediated through symbiosis with microorganisms,” says author and researcher Takefumi Kikusui from the School of Veterinary Medicine.

“Since the gut microbiota influences behavior through the gut-brain axis, we conducted this experiment.”

The publication in iScience reveals that adolescents also had enhanced social competence while positing a link between gut bacteria and empathy. 

According to the researchers, the benefits of living with dogs is likely a result of thousands of years of human-canine co-existence.

Changes in oral microbiome

The study analysis found that a person’s mental health and behavioral scores can be predicted based on whether they lived with dogs at the age of 13. Social issues were noted to be significantly lower among those who had dogs at home compared to those who did not.

Family dogs may enhance adolescents’ mental health and empathy by shaping the gut and oral microbiome.The researchers also examined microbiome samples from teenagers’ mouths. They found that species diversity and richness were similar between those with pet dogs and those without. 

However, the microbiome composition was different. Those with family dogs had an abundance of specific oral bacteria. 

The researchers hypothesized that certain bacteria correlate with the teenagers’ psychological scores.

Testing prosocial behaviour

To test the hypothesis, researchers used laboratory mice with microbiota from teenagers who had pet dogs to investigate the impact on social behavior. These mice were observed to spend more time sniffing other mice in their cage. This is a standard test used to observe prosocial behavior in mice, explain the researchers.

“The most interesting finding from this study is that bacteria promoting prosociality, or empathy, were discovered in the microbiomes of adolescent children who keep dogs,” says Kikusui. 

“The implication is that the benefits of dog ownership include providing a sense of security through interaction, but I believe it also holds value in its potential to alter the symbiotic microbial community.”

The researchers note that further research is needed, however, they confirm that owning a family dog can improve mental health, empathy, and prosocial behavior.

Research into extending the human-dog relationship is ongoing. Scientists have recently identified a biomarker for aging in dogs that reveals biological age and predicts future health issues, findings that may also be applicable to humans. The metabolite may enable healthy life extension.

Research highlights 

In other research at the intersection of emotion and nutritional health, experimenters observed that children displaying kind, caring, and helpful behaviors (being prosocial) are more likely to consume fruit and vegetables as teenagers. They suggest the finding could promote sustained healthy eating into young adulthood.

Meanwhile, a review exploring the connection between gut and mental health found the “strongest proof” yet that the microbiome directly affects brain chemistry, stress responses, and behaviors in animal models.