Cats And Schizophrenia: Here’s The Final Verdict

During the 1970s, an alarming and intriguing issue took place, when psychiatrist Fuller Torrey after learning that multiple sclerosis can be triggered by viruses used to be found in dogs, he then started to make his study leading to the findings that cats’ feces can cause mental illness, specifically schizophrenia. Torrey relates the presence of Toxoplasma gondii in cats; feces as the main etiologic for schizophrenia. When these bacteria enter the body and go to the brain, it can affect the brain’s functioning system and can lead to symptoms of schizophrenia. John M. Grohol, Psy.D. supports this claim of Torrey through his online article titled ‘The Causes of Schizophrenia: It’s Probably Not Genetics,’ saying “Toxoplasma gondii is one such possible cause.”


The First Results

Torrey presented that there is an association of cats to schizophrenics wherein there was an increased level of Toxoplasma antibodies in their blood as compared to the people with no mental ill health. Furthermore, he conducted surveys on the life history of schizophrenics and discovered that most of them lived with cats. Based on his research, it could be concluded that petting cats can cause schizophrenia; but Torrey himself was not convinced that it’s a fact.  


Torrey continued his research, and at his most recent study published last 2015, he again captured the attention of the press, wherein he studied the relationship between cat ownership during a critical age of brain development and the behavioral indicators of later psychosis among persons aged 13 and 18. The study resulted in the non-association of the variables. However, there were still glitches in this study as the statistical analysis has minimized the effect that poverty, or swarming living conditions, can affect the idea that cats cause mental illness. Again, his study did not establish the scientific fact if cats do cause schizophrenia.

It Has Been Corrected!

After two years, a recent study by Solmi et al. (2017), the authors have concluded that owning a cat during pregnancy or childhood is not related to later risk of psychotic symptoms. This was supported in another study conducted in the United Kingdom wherein it revealed no evidence of a relationship between having a cat and the presence of psychotic symptoms at ages 13 and 18 years. This latest study has presented more confined data than the previous ones due to its large number of participants which further proved that having a cat doesn’t amount to an additional risk of developing psychotic symptoms.

These studies have created public curiosity as well as fear, which is a common reaction of people when they found out that something close to them might be the precursor to an impending illness. If you are a cat lover, this can be depressing news. Now that the cloud of ambiguity has been raised, it is safe to say that owning cats cannot make you mentally unstable.

Schizophrenia is caused by three major factors – biological, psychosocial, and environmental elements. According to Jodi Clarke, MA, LPC/MHSP who has 20 years of experience in the field of mental health, “There is a very strong genetic component to schizophrenia.” She added however,  “Genes alone do not completely explain the illness.” There is no single cause for this kind of mental illness or any mental disorders for that matter. It is always the interconnection of several factors. Dina Cagliostro, PhD said, “Schizophrenia is thought to be the result of a culmination of biological and environmental factors. While there is no known cause of schizophrenia, there are genetic, psychological, and social factors thought to play a role in the development of this chronic disorder.


On the other hand, one has to consider proper hygiene and maintain a clean environment when owing cats. As they say, it pays to be a responsible pet owner and maintaining a conducive living condition is one of these actions.



Stockton, N. (2018). Do Cats Cause Schizophrenia? Believe the Science, Not the HypeWIRED. Retrieved 2 March 2018, from

Psychol Med. 2017 Jul;47(9):1659-1667. doi: 10.1017/S0033291717000125. Epub 2017 Feb 22.