A pair of new studies links childhood cat ownership and infection with the parasite Toxoplasma gondii (T. gondii) with later onset schizophrenia and other mental illness. Researchers published their findings in the online Schizophrenia Research and Acta Psychiatrica Scandinavica.
In the Schizophrenia Research study, investigators compared two previous studies that suggested childhood cat ownership could be a possible risk factor for schizophrenia or another serious mental illness with a third, even earlier survey on mental health to see if the finding could be replicated.
“The results were the same,” researchers reported, “suggesting that cat ownership in childhood is significantly more common in families in which the child later becomes seriously mentally ill.”
If accurate, the researchers expect the culprit to be infection with T. gondii, a parasite commonly carried by cats. At this point, though, they are urging others to conduct further studies to clarify the apparent link between cat ownership and schizophrenia.
The Acta Psychiatrica Scandinavica study was a meta-analysis of 50 previously published studies to investigate the prevalence of t. gondii infection in people diagnosed with psychiatric disorders compared with healthy controls.
In cases of schizophrenia, researchers said evidence of an association with T. gondii was “overwhelming,” CBS News reported. Specifically, people infected with T. gondii were nearly twice as likely to be diagnosed with schizophrenia as people never infected with the parasite, according to the report.
The meta-analysis also suggested associations between T. gondii infection and bipolar disorder, obsessive-compulsive disorder, and addiction. No association, however, was found for major depression.
1. Fuller Torrey E, Simmons W, Yolken RH. Is childhood cat ownership a risk factor for schizophrenia later in life? Schizophrenia Research. 2015 April 18. [Epub ahead of print].
2. Sutterland AL, Fond G, Kuin A, et al. Beyond the association. Toxoplasma gondii in schizophrenia, bipolar disorder, and addiction: systematic review and meta-analysis. Acta Psychiatrica Scandinavica. 2015 April 15. [Epub ahead of print].