TWH – There has been a lingering hypothesis out there that cat ownership is linked to schizophrenia-related disorders and psychotic-like experiences (PLE). Researchers agree that much more study is needed into the association, however, they also found evidence that the association might be present. The research was published in the journal, Schizophrenia Bulletin and the news has picked up the findings. Here’s the scoop.
The study, “Cat Ownership and Schizophrenia-Related Disorders and Psychotic-Like Experiences: A Systematic Review and Meta-Analysis,” looked at previous research that had identified a mysterious connection between cat ownership and the likelihood of developing schizophrenia after having a cat. The authors stated, “The study sought to systematically review and meta-analyze publications exploring the connection between cat ownership and schizophrenia-related disorders and psychotic-like experiences, positing that cat ownership might be a risk-modifying factor.”
Vlad demanding attention. Photo Credit: Stefano Ciotti
“Meta-analyze publications” refers to a statistical technique that aggregates previous findings and provides a likelihood of those findings being reliable. To use the technique, researchers must scour previous research to identify studies that showed an association they were interested in. They also had to include studies that rejected the association to avoid bias.
For the current study, the team of Australian researchers scoured the global scientific research spanning from 1980 to 2023, aiming to delve beyond typical concerns like cat bites or mere contact. From nearly 2,000 studies, they meticulously selected 17 scrutinized, distinct studies that were published over the last 44 years in 11 countries to draw their conclusions
Ultimately, they uncovered a correlation between generalized cat ownership and a heightened likelihood of developing schizophrenia-related disorders.
But why? Having a cat has many psychological advantages including stress reduction, reduced anxiety, companionship, and even improved sleep (yes, dog lovers, those benefits are there for you too.)
Moreover, schizophrenia- and similar psychotic disorders – represent a serious cluster of diseases affecting thoughts, behaviors, and feelings. It manifests in enduring delusions, hallucinations, and disorganized thinking. Although its exact cause remains elusive, it appears to stem from a complex interplay of genetic predispositions and environmental influences. The conditions are often treatable but can be debilitating, often hindering a person’s ability to engage in routine tasks and activities.
The association might be connected to a common parasite, Toxoplasma gondii, which causes toxoplasmosis. Toxoplasma is a parasite that can infect all warm-blooded creatures and affects up to a third of the human population. Those with healthy immune systems can keep the parasite in check but often cannot eliminate it entirely. The parasite can be harbored in the brain and other tissues as cysts which begin to multiply if the immune system weakens.
Cats of Rome. Photo Credit: Stefano Ciotti
Individuals harboring latent toxoplasmosis exhibit comparable neurological irregularities. Studies have outlined connections between Toxoplasma infection and heightened inclinations towards risk-taking, aggression, and impulsivity, as well as incidents of suicide and homicide.
However, it’s important to note that studies on human behavior and toxoplasmosis do not establish causation. They do not ascertain whether toxoplasmosis triggers unusual behavior or if such behavior predisposes individuals to acquiring toxoplasmosis. Studies have simply found an association, albeit a well-documented one and that includes schizophrenia.
As to the current study, cats uniquely facilitate the parasite’s reproductive cycle, leading to the release of infectious parasites through feces. Those fecal parasites can endure for years and they can be inhaled or ingested by a cat’s human companion.
“It has been proposed that cat ownership may be a risk-modifying factor for schizophrenia-related disorders and psychotic-like experiences. This study aimed to systematically review and meta-analyze publications that reported the relationship between cat ownership and schizophrenia-related outcomes,” the researchers wrote.
The research team’s findings suggest that individuals exposed to cats had roughly double the likelihood of developing schizophrenia, although they noted that several studies in their analysis had poor association.
Nevertheless, the research findings align with a study conducted the previous year, which indicated that individuals testing positive for Toxoplasma were also twice as likely to develop schizophrenia.
While evidence for a definitive link between cat ownership and schizophrenia remains relatively weak, it still justifies further investigation. What is undeniable is that individuals can contract Toxoplasma through oocysts shed by cats. Additionally, it’s established that toxoplasmosis poses significant health risks to immunocompromised individuals and developing fetuses. Pregnant individuals should avoid handling the litter box, as congenital toxoplasmosis can lead to miscarriage, vision impairment, or birth defects.
“Our findings provide support for the hypothesis that cat exposure is associated with an increased risk of broadly defined schizophrenia-related disorders; however, the findings related to [psychotic-like experiences] as an outcome are mixed,” the researchers concluded.
Teasing out any association will be complicated and likely have other confounding environmental and personal factors. As a result, “There is a need for more high-quality studies in this field.”
Moreover, simple things like handwashing, tending the litter box daily, cleaning surfaces carefully, and teaching children how to avoid infection are easy ways to prevent infections; and the benefits of cat ownership, whether a familiar, a friend, or both, far outweigh the risks.
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