Psychiatrists Assert that Having a Cat in Childhood Doubles the Risk of Schizophrenia

The presence of a cat in a person's life has been linked to more than twice the risk of a mental disorder associated with schizophrenia, according to an analysis of 17 studies dedicated to the topic over the last four decades. The connection is currently not fully understood, but researchers are considering the possibility that human infection with the parasite Toxoplasma gondii from domestic pets, especially cats, may be a contributing factor. 

Science Alert reports on the research conducted by Australian scientists.

Scientists have established a correlation between owning such animals at home and the risk of developing mental disorders in cat owners. According to researchers, the connection lies in the common parasite Toxoplasma gondii. This parasite is often found in domestic cats and can enter the human body through the animal's bite. T. gondii can penetrate the central nervous system and affect neurotransmitters involved in transmitting signals between neurons in the brain. This, in turn, may lead to personality changes, the onset of psychotic symptoms, and the development of mental disorders, including schizophrenia.

The question of the link between toxoplasmosis, transmitted by domestic pets and found in cat owners, and the development of neurological and mental disorders is not a new one. Researchers from the University of Queensland (Australia) found over 1900 articles on this topic published in 11 countries from January 1980 to May 2023, searching through four electronic databases of brain and mental health studies.

Scientists selected 17 studies for their meta-analysis. Their meta-analysis confirmed a correlation between the presence of a cat or kitten in people under 25 years old and an increased risk of disorders related to schizophrenia. The odds ratio was 2.24. High scores for pronounced schizotypal traits were found in the subgroup of participants who had been bitten by their pets.

However, the study's authors emphasize that the analyzed scientific works do not allow for a clear identification of cause and effect in the relationship. In other words, while the results supported the existence of a connection, it is still unclear whether owning a cat actually leads to an increased risk or whether some other factor is associated with both mental health and pet choice. This points to the need for additional qualitative research on the matter.

Among the scientific community, the study has also elicited mixed reactions. Many researchers noted that it did not adequately account for potential influencing factors, such as social and economic status, as well as instances of illness within the family.