Over the past several years there have been a number of studies published that have linked cat ownership or exposure to the parasite Toxoplasma gondii with the development of psychosis such as schizophrenia in humans, including young adolescents. Although almost any animal can be infected with T gondii, cats are important as they play a critical role in maintaining the presence of this parasite. Humans and other animals usually become infected either through eating the flesh of another infected animal, or by eating oocysts (‘eggs’) present in the environment that originate from cat faeces.
Some previous studies of human psychosis and Toxoplasma gondii infection or cat ownership have shown an epidemiological association between them (that is, humans with certain psychosis may be more likely to be infected with Toxoplasma gondii and/or have a pet cat. However, observations such as these are not able to establish cause and effect and it is not clear if Toxoplasma gondii causes the psychosis.
A new study from the UK has looked carefully at this question by following a large group of children through to early adulthood. This study found that cat ownership during pregnancy or during early life (4-10 years of age) had no relationship with the development of psychoses in children at 13 or 18 years of age. The reassuring conclusion from the study was that there was strong evidence that cat ownership during pregnancy or early childhood had no relationship to the development of psychosis during early or late adolescence.
This was a rigorous and well conducted study involving several thousand children and as such these results are encouraging. While there may be a link between exposure to Toxoplasma gondii and certain psychotic disorders, there appears to be no increased risk as a result of cat ownership.
To view the study click here