Meta-analysis indicated risk of schizophrenia in cat owners
The presence of a cat or a cat at home in people's childhood or youth subsequently approximately doubled the probability of developing schizophrenia. Such a conclusion was made by Australian scientists following the results of meta-analysis of scientific papers on this topic for the last 40+ years.
According to the researchers, whose work was published by the journal Schizophrenia Bulletin, the relationship lies in the common parasite Toxoplasma gondii. It is often found in domestic cats and can enter the human body through an animal bite. T. gondii is able to penetrate the central nervous system and affect neurotransmitters, which are involved in the transmission of signals between neurons in the brain. This, in turn, can lead to personality changes, psychotic symptoms and the development of psychotic disorders, including schizophrenia.
It is not for the first time that scientists have raised the question of the connection between toxoplasmosis transmitted by pets and the development of neurological and psychiatric disorders. According to the results of a search in four electronic databases of scientific papers, experts in the field of brain and mental health from the University of Queensland (Australia) found more than 1900 articles mentioning this topic, published in 11 countries from January 1980 to May 2023.
The Australian researchers selected 17 papers based on text completeness and other research requirements. Their meta-analysis confirmed a correlation between having a cat or cats under the age of 25 and an increased risk of developing schizophrenia-related disorders. The pooled odds ratio was 2.24.
The authors of the review noted that in one of the reviewed studies, which involved 354 psychology students from the United States, it was not possible to find a direct link between the presence of a cat in the house and scores on the schizotypy scale. The latter is often used as one of the tools for diagnosing schizophrenia. However, high scores on the schizotypal traits were found in the subgroup of participants who had been bitten by pets.
Although the researchers from the University of Queensland have done extensive work, it has generated mixed reactions among colleagues in the scientific community. Many researchers criticized the review, noting that it did not adequately consider contributing factors that could potentially influence the results, such as social and economic status and family history of disease.
An example is one of the studies conducted in Britain. In it, scientists found that in children from four to 10 years of age who had contact with cats and cats, later, at the age of 13, the presence of such experiences was associated with an increase in psychotic experiences. However, when the researchers made adjustments for distorting factors, the findings did not hold up.