A new study published in the Schizophrenia Bulletin found an intriguing connection between cat ownership and the risk of developing schizophrenia-related disorders and psychotic-like experiences. This systematic review and meta-analysis offers a new understanding of a potential environmental risk factor for mental health disorders.
The study meticulously analyzed data from publications spanning over four decades, focusing on the relationship between cat ownership before the age of 25 and schizophrenia-related outcomes. The results found that cat ownership was associated with double the likelihood of developing schizophrenia-related disorders. This is particularly significant considering the widespread prevalence of cat ownership globally.
Toxoplasmosis
A key aspect of this relationship is the role of Toxoplasma gondii (T. gondii), a protozoan parasite commonly found in domestic cats. T. gondii infection, known as toxoplasmosis, has been linked to various neurological disorders, including schizophrenia. Cats, as hosts of T. gondii, can shed oocysts in their feces, which can contaminate soil, water, or food sources. Humans can become infected by ingesting contaminated substances, leading to the formation of tissue cysts in the brain and other organs.
The study’s results align with previous research suggesting a connection between T. gondii infection and increased schizophrenia risk. The parasite’s ability to persist in the central nervous system and induce physiological changes raises questions about its potential impact on brain function and mental health.
However, it is crucial to approach these findings with a nuanced understanding. While the study highlights an association, it does not establish a direct cause-and-effect relationship. The complexity of schizophrenia, a disorder influenced by a multitude of genetic and environmental factors, means that cat ownership is likely just one of many elements contributing to the risk profile. Nonetheless, this study suggests that mental health clinicians may want to consider latent infections, such as toxoplasmosis, as a potential cause of serious mental health conditions.
Prevention
The study underscores the importance of public awareness regarding toxoplasmosis, especially for cat owners. Simple measures, such as proper hand hygiene after handling cats or cleaning litter boxes and ensuring cats are kept indoors to prevent hunting and potential infection, can significantly reduce the risk of T. gondii transmission.
This research opens up new avenues for understanding the environmental factors contributing to schizophrenia and related disorders. While cat ownership has been identified as a potential risk factor, it is essential to view this in the broader context of the multifactorial nature of mental health disorders. Ongoing research and public health education about toxoplasmosis and its prevention will be crucial in unraveling the complexities of this relationship. For cat owners and mental health professionals alike, this study offers insights and a call for continued vigilance and more research.
References
John J McGrath, Carmen C W Lim, Sukanta Saha, Cat Ownership and Schizophrenia-Related Disorders and Psychotic-Like Experiences: A Systematic Review and Meta-Analysis, Schizophrenia Bulletin, 2023; sbad168, https://doi.org/10.1093/schbul/sbad168
Author’s Note: This post was originally featured on Psychology Today.
Christopher M. Palmer, M.D., is a Harvard psychiatrist and researcher working at the interface of metabolism and mental health. He is the director of the Department of Postgraduate and Continuing Education at McLean Hospital and an Assistant Professor of Psychiatry at Harvard Medical School.
