Researchers from Australia have discovered a link between cat ownership and the risk of schizophrenia after analyzing 17 studies published over the past 44 years, from 11 countries, including the United States and the United Kingdom.
Multiple Findings on the Connection Between Cats and Schizophrenia
Researchers found a correlation between cat ownership and an increased incidence of schizophrenia-related disorders – (Photo: Hepper)
Psychiatrist John McGrath and his colleagues, all from the Queensland Mental Health Research Center, explained: “We found a connection between cat ownership and an increased rate of schizophrenia-related disorders.”
The idea that owning a cat may be associated with a higher risk of schizophrenia was proposed in a 1995 study, which suggested that exposure to a parasite called Toxoplasma gondii could be the cause.
However, thus far, the research has yielded various conclusions.
Some studies have found that proximity to cats during childhood may increase an individual’s risk of developing schizophrenia. Nonetheless, not all studies have identified this link.
Several researchers have also associated cat exposure with higher scores on measures of schizophrenia-related traits, affecting thoughts, emotions, and behaviors, as well as psychotic-like experiences. Conversely, other studies have found no such association.
To gain a clearer picture, McGrath and his team suggest that all research on these topics needs thorough review and analysis. Toxoplasma gondii is a nearly harmless parasite that can be transmitted through undercooked meat or contaminated water.
The bite of an infected cat or contact with infected cat feces can also transmit Toxoplasma gondii.
It is estimated that around 40 million people in the United States may be infected, often without any symptoms. Meanwhile, researchers continue to discover more peculiar effects that this infection may cause.
Once inside the human body, Toxoplasma gondii can invade the central nervous system and affect neurotransmitters. This parasite has been linked to personality changes, the onset of psychotic symptoms, and several neurological disorders, including schizophrenia.
More Research Needed for Conclusions
The research team stated: “After adjusting for covariates, we found that individuals exposed to cats had approximately double the risk of developing schizophrenia.”
There are several important considerations here, such as the fact that 15 out of the 17 studies were case-control studies. This type of research cannot establish cause and effect, and often does not account for factors that may influence both exposure levels and outcomes. Some of the studies reviewed were of low quality, which the authors also highlighted.
One study in the United States, involving 354 psychology students, found no link between cat ownership and schizophrenia scores. However, those who were bitten by cats scored higher than those who were not.
Another study, which included individuals with and without mental disorders, found a connection between cat bites and higher scores on tests measuring specific psychological experiences. However, they suggested that other pathogens, such as Pasteurella multocida, could be alternative causes.
Researchers agree that better and broader studies are needed before any definitive explanations can be made.
The authors wrote: “In summary, our assessment provides evidence supporting the association between cat ownership and schizophrenia-related disorders. More high-quality research, based on large representative samples, is needed to better understand cat ownership as a potential factor affecting the risk of developing mental disorders.”
