Schizophrenia can produce persistent delusions, hallucinations, and disorganized thinking. The precise cause is unknown but seems to involve a combination of genetics and environmental risk factors. One environmental factor may be an infectious agent, such as the common parasite Toxoplasma gondii, which causes toxoplasmosis.
Since cats can transmit Toxoplasma to humans, scientists have been investigating whether there is a link between cat ownership and schizophrenia. Many studies have tried to answer this question over the past 50 years; some studies show an association, but others do not. Researchers at the University of Queensland in Australia recently reanalyzed all these studies to determine the current consensus.
