Study finds no link between cat ownership and schizophrenia, despite alarming headlines

As if parents of young children didn’t have enough things to worry about, here’s another: some scientists say they think pet cats might increase a kid’s risk of developing schizophrenia.

But there’s good news out of this growing field of research, which focuses on the links between a cat-borne parasite that causes toxoplasmosis and mental health disorders. A new study of about 5,000 children in Britain found no evidence that cat ownership during gestation or childhood was associated with psychotic experiences that can be early signs of mental illness - such as hallucinations or delusions of being spied on - when they were teenagers.

The study, which was published in the journal Psychological Medicine, is the latest in a field that’s yielded many alarmist headlines based on correlations, but not concrete conclusions, about cats making people crazy. And it amounts to a big “not so fast.”

“Many people own cats, which are an important part of the life of many families,” co-author James Kirkbride, a psychiatric epidemiologist at University College London, said in an email. “Our findings should reassure people that owning a cat in pregnancy or childhood is not related to later risk of psychotic symptoms.”

The cat-toxoplasmosis-psychosis nexus has gotten a lot of attention in recent years, but it’s hardly well understood.

It’s clear that the parasite that causes toxoplasmosis infections in people, T. gondii, depends entirely on cats, because it reproduces only in cat intestines and is spread via feline faeces. And there’s “good evidence,” the study’s authors write, that T. gondii infections are associated with psychosis. So some researchers hypothesise that owning cats in childhood increases the risk of developing mental illnesses, particularly schizophrenia, and a handful of studies have supported this idea. But people can also become infected with T. gondii from undercooked meat or contaminated water.