Having a dog in the household during childhood may significantly decrease the risk of schizophrenia later in life, suggests a study published online in PLOS One.
“There are several plausible explanations for this possible ‘protective’ effect from contact with dogs — perhaps something in the canine microbiome that gets passed to humans and bolsters the immune system against or subdues a genetic predisposition to schizophrenia,” said lead author Robert Yolken, MD, chair of the Stanley Division of Pediatric Neurovirology and professor of neurovirology in pediatrics at the Johns Hopkins Children’s Center, Baltimore, Maryland.
Researchers from Johns Hopkins Medicine and the Sheppard Pratt Health System, also in Baltimore, looked at dog and cat ownership during the first 12 years of life in 396 adults with schizophrenia, 381 adults with bipolar disorder, and 594 adults without a psychiatric disorder who served as controls.
People with a pet dog in the household before they turned 13 were up to 24% less likely to be diagnosed with schizophrenia in adulthood, the findings suggested.
“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,” Dr. Yolken said.
The study found no significant link between dog ownership and bipolar disorder risk. Furthermore, it did not identify any overall significant associations between cat ownership and a later diagnosis of schizophrenia or bipolar 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,” Dr. Yolken pointed out. “This indicates that the time of exposure may be critical to whether or not it alters the risk.”
Yolken R, Stallings C, Origoni A, et al. Exposure to household pet cats and dogs in childhood and risk of subsequent diagnosis of schizophrenia or bipolar disorder. PLOS One. 2019 December 2;14(12):e0225320.