Cat Ownership Linked to Increased Risk of Schizophrenia, Study Suggests : ScienceAlert
A 2023 review of existing research indicates that having a cat as a pet is linked to higher odds of schizophrenia-related conditions. However, researchers emphasize that these findings show an association rather than a direct cause-and-effect relationship.
The team from the Queensland Centre for Mental Health Research in Australia notes that better studies are required before firm conclusions can be drawn. They caution that this does not mean a pet cat is secretly impacting the health of its owner.
The Scope of the Research
Psychiatrist John McGrath and colleagues conducted a review and meta-analysis examining studies published over the last 44 years. Their research spanned 11 countries, including the United Kingdom and the United States.
After reviewing 17 studies, the team found “a significant positive association between broadly defined cat ownership and an increased risk of schizophrenia-related disorders.”
The researchers noted that after adjusting for covariates, individuals exposed to cats had approximately twice the odds of developing schizophrenia. However, the data remains inconsistent; for example, one study found no significant association for cat ownership before age 13, but did find a link specifically between the ages of 9 and 12.
The Role of Toxoplasma gondii
The hypothesis that cat ownership could be linked to schizophrenia risk dates back to 1995, suggesting an infection passed from animals to humans. One possible explanation is exposure to Toxoplasma gondii.
This parasite can be transmitted to humans through contaminated water, undercooked meat, or contact with infected cat feces. Once inside the body, T. Gondii can persist in the central nervous system and may influence neurotransmitter systems.
While the parasite has been linked to the emergence of psychotic symptoms, personality changes, and some brain disorders, a link does not prove that T. Gondii causes these changes or that the parasite was transmitted via a cat.
Other Potential Factors and Limitations
Beyond parasites, some research has explored other triggers. One study of 354 psychology students in the U.S. Found no association between cat ownership and schizotypy scores, but did find higher scores among those who had received a cat bite.
Other research involving individuals with and without mental disorders also connected cat bites to higher scores on tests measuring particular psychological experiences. Authors of that study suggested other pathogens, such as Pasteurella multocida, may be responsible.
The researchers highlighted significant limitations in the current body of work, noting that 15 of the 17 reviewed papers were case-control studies. This research design cannot show cause and effect and often fails to account for factors that may affect both exposure and outcome.
Looking Forward
The research, published in Schizophrenia Bulletin, concludes that the field requires better-designed research that can more carefully account for confounding factors.
Future studies based on large, representative samples may be a possible next step to better understand if cat ownership is a candidate risk-modifying factor for mental disorders.
Frequently Asked Questions
Does owning a cat cause schizophrenia?
No. The research shows an association, not cause and effect. The researchers emphasize that better studies are needed before any firm conclusions can be drawn.
How is Toxoplasma gondii transmitted to humans?
It can be passed through an infected cat’s feces, as well as through contaminated water or undercooked meat.
What are the general causes of schizophrenia?
The exact causes are varied, complex, and mostly unknown, but appear to involve a combination of biological changes in the brain, environmental factors, and genetics.
How do you think the bond between pets and owners influences our perception of health risks?