A study by John Hopkins Medicine explores the link between exposure to a household pet cat or dog during the first 12 years of life and a later diagnosis of schizophrenia or bipolar disorder.
Researchers found a statistically significant decrease in the risk of a person developing schizophrenia if exposed to a dog early in life.
Across the age range studied, there was no significant link between dogs and bipolar disorder, or between cats and either psychiatric disorder.
Researchers have said more studies need to be carried out to confirm the findings and identify the factors behind any strongly-supported links.
Serious psychiatric disorders have been associated with alterations in the immune system linked to environmental exposures in early life.
Previous studies have identified early life exposures to household pets and environmental factors that may alter the immune system through various means such as allergic responses, contact with animal bacteria and viruses, changes in a home’s microbiome and pet-induced stress reduction effects on human brain chemistry.
Researchers therefore decided to explore early exposure to household pets as they are often among the first things with which children have close contact.
The John Hopkins Medicine study looked at a population of 1,371 men and women between the ages of 18 and 65 that consisted of 396 people with schizophrenia, 381 with bipolar disorder and 594 controls.
Study participants were asked if they had a household pet cat or dog or both during their first 12 years of life.