Growing up in the same household as a pet cat can increase the risk of experiencing a psychotic episode later in life, but only for men. According to a new study, this increased likelihood of mental illness could be caused by a common parasite called toxoplasmosis gondiiwhich can be transmitted to humans who come into contact with cat poop.
the link between T. gondii and psychosis has been hotly debated for decades, with some studies suggesting a higher prevalence of schizophrenia among those infected with the parasite, while others have failed to identify such a link. Sometimes present in raw meat or contaminated drinking water, the nasty little protozoan can infect all warm-blooded animals and is very prevalent among humans.
Although the vast majority of infected individuals have no symptoms and are not even aware that they carry the parasite, some people can develop moderate to severe complications, such as fever or breathing problems. Previous studies have also shown that children who grow up in homes with cats are more likely to suffer from psychiatric disorders as adults.
To investigate, the authors of the new study published in the Journal of Psychiatric Research interviewed 2,206 adults from downtown Montreal about childhood cat ownership, as well as their history of psychotic episodes. Participants were also asked about other risk factors for psychosis, such as head trauma, smoking, and the number of times they moved house as a child.
“Childhood cat ownership was associated with greater expression of psychosis in adulthood, but only in the presence of certain factors,” the authors write. Specifically, they observed an increased risk of psychosis in men who owned outdoor cats as children, but found no such link for women or adults who owned domestic cats in their youth.
Importantly, the researchers did not analyze the participants’ blood for T. gondii antibodies, meaning they can’t be sure that this heightened risk is linked to the parasite. However, their results suggest this may be the case, as cats can only catch the parasite by hunting infected rodents, which is obviously something that outdoor cats do more often than domestic cats.
The researchers also note that cat ownership alone may not increase the risk of psychosis, as the greatest increase in the likelihood of psychotic episodes was seen in those who had a history of head trauma, moved house several times in childhood, and owned a hunt. to rodents. cat. Furthermore, the authors are unable to explain why only males appear to be affected and do not provide evidence of any neurobiological mechanism linking T. gondii to psychiatric disorders.
That said, previous studies have indicated that the parasite can interfere with a type of brain cell called microglia and disrupt the formation of neurological connections, which may explain how T. gondii affects the mind.
Overall, the link between cat ownership and psychosis remains a point of contention, although anyone concerned about the risk posed by cat ownership T. gondii can minimize the chance of infection by washing their hands thoroughly after cleaning the cat’s litter box.