Dear doctors, my wife read somewhere that when children grow up with a dog in the house, it can protect them from schizophrenia. I know having a pet can help kids develop responsibility, but preventing mental illness seems like a stretch. Is this psychologically based or something else?
Dear Reader: Your wife is referring to the results of a study published several years ago that found a link between living with a dog in very early childhood and a reduced risk of developing schizophrenia later in life. As you can imagine, these findings generated quite a few headlines.
Schizophrenia is a mental illness that interferes with a person’s sense of reality. When left untreated, it is often devastating and prevents someone from fully participating in everyday life. The condition usually appears between the ages of 16 and 30. Early symptoms often include visual and auditory hallucinations, disturbed thought patterns, delusions, and paranoia.
Although the causes of schizophrenia are still unclear, both genetics and brain structure have been shown to play a role. More recently, researchers have begun to investigate a potential connection to the gut microbiome—specifically, whether certain environmental exposures may affect brain development and thus play a role in who develops serious psychiatric illness and who does not.
Childhood pets are an early source of exposure to a number of harmless microbes as well as potential allergens. We are now learning that through the gut microbiome, such exposure can have a positive effect on some children’s immune systems. This led the researchers in this study to wonder whether living with a cat or dog during the first 12 years of life could have an effect on mental health. Specifically, they looked for any correlations with a diagnosis of schizophrenia or bipolar disorder. The latter is a mental health condition marked by sudden and extreme changes in mood, energy, and concentration. Like schizophrenia, bipolar disorder often appears in adolescence and makes it difficult to successfully cope with the tasks of everyday life.
In this study, researchers used health data from 396 adults diagnosed with schizophrenia and 381 adults diagnosed with bipolar disorder. They also included 594 adults without mental disorders to serve as a control group. Participants ranged in age from 18 to 65 years, were in good health, and had no history of drug use. All were asked to detail their personal history with childhood pets.
When the researchers analyzed the data, they were surprised to find a statistically significant link between the presence of a family dog in early childhood and a reduced risk of developing schizophrenia later in life. They did not find the same association in study participants with bipolar disorder or among those whose childhood pet was a cat. Further study is needed to understand the significance of this finding. But among the theories under closer scrutiny will be whether beneficial microorganisms in the dogs’ microbiomes may have provided a measure of protection against schizophrenia later in life.
Eve Glazier, MD, MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Koh, MD, is an internist and assistant professor of medicine at UCLA Health. Send your questions to [email protected] or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Due to the volume of mail, we cannot personal responses are provided.