By analysing a previously unused questionnaire of from 1982 filled in by 2,125 families that belonged to the National Institute of Mental Illness, scientists discovered that 50.6 per cent of people who developed schizophrenia owned a cat in childhood. These results were similar to two other studies in the 1990s, experts said.
Around 1 in 100 people will experience schizophrenia in their lifetime, but it is most commonly diagnosed between the ages of 15 and 35, according to the NHS.
Schizophrenia is a long-term mental illness that can cause symptoms including hallucinations, delusions, and changes in behaviour.
And while the overall instance of schizophrenia from the study is low, scientists will now attempt to understand why this link exists. However, researchers believe that Toxoplasma gondii, a single-cell parasite present in some cats, may be the cause.
E. Fuller Torrey, a researcher from the Stanley Medical Research Institute who took part in the study, told the Huffington Post: “T. gondii gets into the brain and forms microscopic cysts. We think it then becomes activated in late adolescence and causes disease, probably by affecting the neurotransmitters.”
Toxoplasma gondii can live in many different species but it can only complete its life cycle in cats, as the animals secrete the parasite in their faeces.
Studies have also revealed that Toxoplasma is beneficial to cats, in that it changes the behaviour of mice and makes them more likely to be eaten, thereby completing parasite’s complex life-cycle.