Could owning a cat bring health risks? Study suggests it may double the chances of a ‘serious mental health condition’

Owning a cat may double a person’s risk of developing schizophrenia-related disorders, according to a new meta-analysis of 17 studies. Researchers from the Queensland Centre for Mental Health Research in Australia found a significant link between cat exposure and later diagnosis of psychotic illnesses, though they caution that association does not equal causation.

The study, published in Schizophrenia Bulletin, reviewed research conducted over the past four decades across 11 countries, including the United States and the United Kingdom. Psychiatrist John McGrath and his team reported that, after adjusting for other variables, people exposed to cats had about twice the odds of later developing psychotic illnesses compared to those who were not exposed.

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How the infection can be spread by cat

One of the main hypotheses involves Toxoplasma gondii, a parasite commonly carried by cats. It can spread through cat feces, bites, or even undercooked meat and contaminated water. Once inside the body, T. gondii may reach the central nervous system and influence neurotransmitters, potentially triggering personality changes, psychotic symptoms, or psychiatric disorders.


However, researchers emphasize that while the link is biologically plausible, “not all studies have found this association.”

What is Schizophrenia?

Schizophrenia is a ‘serious mental health condition’ that affects a person’s thinking, emotions, and behavior,’ according to the Mayo Clinic. The disorder can cause a combination of hallucinations, delusions, and disorganized thinking and behavior.

• Hallucinations involve seeing or hearing things that others do not perceive.
  
  
• Delusions are strong beliefs in things that are not true.
  
  

These symptoms can make it difficult for people with schizophrenia to stay connected to reality, often interfering with daily life.

Management of schizophrenia typically requires lifelong treatment, which may include medication, talk therapy, and support to help individuals handle everyday activities and maintain a functional life.

Limitations and conflicting evidence

Despite the striking claim of doubled risk, the review has notable limitations. Fifteen of the 17 studies were case-control, comparing people with schizophrenia to those without, rather than following participants over time. This design cannot establish cause and effect. Many studies were also judged to be of low quality, with inconsistent results.

Some studies contradicted the overall finding. For instance, a US study of college students found no clear link between owning a cat and scoring higher on schizotypy scales (traits related to schizophrenia).

Timing of exposure may also matter. One study focusing on cat ownership during childhood (ages 9–12) reported stronger associations than studies with broader age ranges, hinting at a potential critical exposure window that remains undefined.

Contrasting evidence

As stated earlier, not all research supports the cat-schizophrenia link. A 2017 study from University College London, which followed nearly 5,000 individuals from birth to age 18, found no significant association between cat exposure and later psychotic symptoms. That study controlled for socioeconomic status and other factors, raising questions about the robustness of the connection.

While the findings may worry proud cat parents, experts caution against overreaction, as the study findings are mixed. The evidence shows a statistical association, not a direct cause-effect relationship. The researchers note, “There is a need for more high-quality studies in this field.”

FAQs

Can owning a cat increase the risk of schizophrenia?
Research suggests a potential link between cat ownership and schizophrenia-related disorders, possibly due to exposure to the parasite Toxoplasma gondii. However, association does not mean causation, and results across studies are mixed.

How does Toxoplasma gondii from cats affect humans?
Toxoplasma gondii can be transmitted through cat feces, bites, undercooked meat, or contaminated water. Once in the body, it may reach the central nervous system and influence neurotransmitters, which could affect behavior or mental health in some cases.

Should cat owners be worried about schizophrenia?
Experts advise caution but not panic. While some studies suggest an increased risk, the evidence is inconsistent, and owning a cat does not directly cause schizophrenia. Maintaining hygiene and regular vet care can reduce any potential risks.