A surprising new meta-analysis is stirring fresh debate about the link between cat ownership and schizophrenia-related disorders. Researchers from the Queensland Centre for Mental Health Research in Australia reviewed 17 studies spanning 11 countries over four decades, revealing that people exposed to cats had about twice the odds of developing psychotic illnesses compared to those without cat exposure.
These findings, published in Schizophrenia Bulletin, highlight a statistically significant association but do not prove that cats cause schizophrenia.
Schizophrenia is a chronic mental disorder affecting about 23 million people worldwide, or roughly 1 in 345 individuals. Its onset typically occurs in late adolescence or early adulthood, with men often affected earlier than women. Schizophrenia causes disruptions in thinking, perception, and emotional responsiveness, making it one of the leading causes of disability globally. Despite its impact, many people with schizophrenia do not receive adequate mental health care, highlighting a persistent treatment gap worldwide.
The main hypothesis centers on Toxoplasma gondii, a parasite commonly hosted by cats that can enter the human body via contact with cat feces, bites, or contaminated food and water. T. gondii can affect the brain’s neurotransmitters, potentially triggering psychotic symptoms. However, researchers caution that association does not mean causation, and many analyzed studies had methodological limitations, including reliance on case-control designs that do not establish cause and effect.
Adding complexity, some studies found no clear link between general cat ownership and psychosis, while others suggest a critical exposure window in childhood may matter most. For example, cat ownership between ages 9–12 was more strongly linked to schizophrenia risk than exposure at broader ages. Conflicting results and low-quality evidence mean that further high-quality, large-scale research is needed to clarify whether cat exposure is a true risk factor.
For now, cat owners should not panic but exercise sensible hygiene, such as regular litter cleaning and handwashing after handling cats or their waste. This evolving research broadens our understanding of environmental contributors to mental illness, emphasizing that psychiatric conditions arise from a complex interplay of genetics, infections, and lifestyle factors.
REFERENCE: 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, Volume 50, Issue 3, May 2024, Pages 489–495, https://doi.org/10.1093/schbul/sbad168
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