A comprehensive review of 17 studies suggests that owning a cat may significantly increase the risk of developing schizophrenia-related disorders, potentially doubling an individual’s chances. The analysis, conducted by researchers at the Queensland Centre for Mental Health Research in Australia, examined decades of research across 11 countries, including the US and the UK.
The Parasite Connection: Toxoplasma gondii
The potential link stems from exposure to Toxoplasma gondii, a common parasite found in cat feces and undercooked meat. While generally harmless, T. gondii can infiltrate the central nervous system, influencing neurotransmitters and potentially altering behavior. The parasite has been implicated in personality changes, psychotic symptoms, and even neurological disorders, though a direct causal relationship remains unproven.
Mixed Research Findings
The evidence is not conclusive. Some studies indicate a correlation between childhood cat exposure and increased schizophrenia risk, while others find no association. Inconsistent results may stem from varying methodologies, sample sizes, and control factors. One study found no link between owning a cat before age 13 and later developing schizophrenia, but a significant connection when narrowing the exposure period to ages 9-12.
The Role of Cat Bites
Interestingly, research suggests that cat bites may be more strongly associated with certain psychological traits. One US study involving psychology students found no link between cat ownership and schizotypy scores (a measure of personality traits related to schizophrenia), but those who had been bitten by a cat scored higher on related scales. This suggests that other pathogens, such as Pasteurella multocida (found in cat saliva), might also play a role.
Study Limitations
The majority of studies analyzed were case-control studies, which cannot establish cause and effect. Additionally, many studies were deemed low quality, with inconsistent results. Researchers emphasize the need for larger, more representative samples and better-controlled studies to determine the true extent of the association.
What This Means
While the findings are concerning, they do not prove that cats cause schizophrenia. The association may be due to other factors, such as underlying genetic predispositions or environmental influences. However, the consistent signal across multiple studies warrants further investigation.
The researchers conclude that more high-quality studies are needed to understand cat ownership as a potential risk-modifying factor for mental disorders. The review supports a link, but definitive conclusions require stronger evidence.
“Our review provides support for an association between cat ownership and schizophrenia-related disorders. There is a need for more high-quality studies, based on large, representative samples to better understand cat ownership as a candidate risk-modifying factor for mental disorders.”
