Schizophrenia: growing up with a dog would reduce the risks

This should finish convincing parents hesitant to offer a dog to their children. If it has already been scientifically proven that having a dog reduces anxiety and reduces the risk of strokes and heart attacks, it also seems that children who have grown up with a dog have a lower risk of developing schizophrenic disorders. later. The results of this new study were published on December 2 in the journal Plos One.

In the past, several studies have identified early exposure to pet cats and dogs as environmental factors that can alter the immune system. Whether through contact with zoonotic bacteria and viruses, changes in a home’s microbiome, or the effects of stress reduction on the human brain. However, this “immune modulation” could modify the risk of developing psychiatric disorders to which an individual is genetically predisposed.

“Serious psychiatric disorders have been associated with alterations in the immune system linked to early environmental exposures, and since pets are often among the first things children come into close contact with, it made sense for us to explore the possibilities of a link between the two”, explains doctor Robert Yolken, of the Johns Hopkins Children’s Center (Baltimore, United States). He and his colleagues at the Sheppard Pratt Health System (Baltimore, USA) therefore decided to study the subject.

Up to 24% less risk

To do this, they followed 1,371 men and women aged 18 to 65, of whom 396 had schizophrenia and 381 with bipolar disorder. During the study, they asked participants if they had had a dog and/or a cat during their first 12 years. After taking into account their age, gender, ethnicity, place of birth, and economic status, they were surprised to notice that those who had been exposed to a pet dog before their 13^th birthday were up to 24 times less likely to ever be diagnosed with schizophrenia.

“The greatest apparent protective effect was seen in children who had a pet dog at birth or who were first exposed after birth but before age 3,” says Robert Yolken. On the other hand, no significant link was observed between dogs and bipolar disorders.

“We found a slightly higher risk of developing both disorders in those who first came into contact with cats between the ages of 9 and 12, says Yolken. This indicates that exposure time may be critical in determining whether or not it changes risk.”

Link between toxoplasmosis transmitted by cats and mental disorders

This phenomenon could be explained by toxoplasmosis, a disease in which cats can transmit the parasite to humans through their feces. In 2003, by sifting through numerous studies on the subject, Yolken and a colleague had shown that there was a statistical link between a person exposed to the parasite that causes toxoplasmosis and an increased risk of schizophrenia.

For years, pregnant women have been recommended not to change cat litter to prevent the disease from passing through the placenta to the fetus. The risk being to induce a miscarriage or psychiatric disorders in a child born with the infection.

But while most studies to date have focused on a potential link between early exposure to cats and the development of psychiatric disorders, this one is one of the first to look at contact with dogs.

In France, 600,000 people with schizophrenia

Other work is therefore necessary to confirm these results and define more precisely the real risks of developing psychiatric disorders by exposing babies to pets. “A better understanding of the mechanisms underlying the associations between pet exposure and psychiatric disorders would allow us to develop appropriate prevention and treatment strategies,” concludes Robert Yolken.

At present, schizophrenia affects around 0.7% of the world’s population, including 600,000 people in France. According to Inserm, it most often occurs in adolescence, between the ages of 15 and 25. In 35% to 40% of cases, it is first manifested by delirious puffs. In addition to delusions and hallucinations, most often, patients isolate themselves, make incoherent remarks and are completely unable to plan simple tasks, which greatly complicates their daily lives.

However, with appropriate and early management, it is possible to control this disease. According to Inserm, after a few years of treatment, approximately one third of patients are in lasting remission and can resume a normal social, emotional and professional life.