Pet Dogs Lessen Risk of Schizophrenia

Research just published in the journal PLOS One revealed a surprising finding: People exposed to a pet dog in childhood are significantly less likely to later be diagnosed with schizophrenia.

Scientists from Baltimore-based Johns Hopkins Children’s Center and the Sheppard Pratt Health System explored the connection between having a pet dog or cat during the first 12 years of life and later diagnoses of either schizophrenia or bipolar disorder. The study involved both male and female subjects, between the ages of 18 and 65. Some had schizophrenia, others had bipolar disorder, and a control group had neither. All were asked if they had a pet cat or pet dog in their home growing up, before age 12. Having a pet is very common: There are 94 million pet cats and 90 million pet dogs in the U.S. (Here are 5 Ways to Bond with Your Pooch.)

The Results

Being around a pet dog was linked to as much as a 24 percent decrease in the likelihood of being later diagnosed with schizophrenia. “The largest apparent protective effect was found for children who had a household pet dog at birth or were first exposed after birth but before age 3,” wrote the study’s lead author, Dr. Robert Yolken.

There was no link found between exposure to a dog and later developing bipolar disorder, nor any significant links between cats and either disorder. “However, we did find a slightly increased risk of developing both disorders for those who were first in contact with cats between the ages of 9 and 12,” Yolken wrote. “This indicates that the time of exposure may be critical to whether or not it alters the risk.”

Why the Connection?

“There are several plausible explanations for this possible ‘protective’ effect from contact with dogs,” Yolken wrote in the study. “Perhaps something in the canine microbiome that gets passed to humans and bolsters the immune system against or subdues a genetic predisposition to schizophrenia.”

Past research on pet dogs and cats also suggest that they may alter our immune systems, whether by an allergy response, contact with bacteria and viruses, or even the stress reduction that pets can have on the human brain. (See 10 Ways Pets Improve Mental Health.)

Future research will seek to understand the exact way that exposure to pets is associated with psychiatric disorders.

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