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New study debunks crazy cat lady theory

In good news for single women everywhere, a new study has cleared cats of causing mental illness.

03 Mar 2017

In good news for single women everywhere, a new study has cleared cats of causing mental illness.

Cats came under the microscope after a number of scientific studies linked Toxoplasma Gondii (T. Gondii) infection with mental health issues, including schizophrenia, suicide and intermittent rage disorder.

Cats carry T. Gondii, prompting speculation that cat ownership may put people at increased risk of mental illness, by exposing them to it.

“However, only a handful of small studies have found evidence to support a link between owning a cat and psychotic disorders, such as schizophrenia,” researchers Francesca Solmi and James Kirkbride, from University College London, wrote for The Conversation UK.

“And most of these investigations have serious limitations. For instance, they relied on small samples, did not specify how participants were selected, and did not appropriately account for the presence of missing data and alternative explanations. This can often lead to results that are born out of chance or are biased.”

To further investigate, Ms Solmi and Dr Kirkbride conducted a study using data from approximately 5,000 children who took part in the Avon Longitudinal Study of Parents and Children between 1991 and 1992, and have been regularly followed up for further health information.

“So, unlike previous studies, we were able to follow people over time, from birth to late adolescence, and address a number of the limitations of previous research, including controlling for alternative explanations (such as income, occupation, ethnicity, other pet ownership and over-crowding) and taking into account missing data,” Ms Solmi and Dr Kirkbride wrote.

They studied whether mothers who owned a cat while pregnant; when the child was four years old; and 10 years old, were more likely to have children who reported psychotic symptoms, such as paranoia or hallucinations, at age 13 and 18 years of age.

“So are cats bad for your mental health? Probably, not,” they concluded.

“We found that children who were born and raised in households that included cats at any time period – that is, pregnancy, early and late childhood – were not at a higher risk of having psychotic symptoms when they were 13 or 18 years old.

“This finding in a large, representative sample did not change when we used statistical techniques to account for missing data and alternative explanations. This means that it is unlikely that our results are explained by chance or are biased.”

However, there is evidence linking exposure to T. Gondii in pregnancy to a risk of miscarriage and stillbirth, or health problems in the baby.

“In our study, we could not directly measure exposure to T. Gondii, so we recommend that pregnant women should continue to avoid handling soiled cat litter and other sources of T. Gondii infection, such as raw or undercooked meats, or unwashed fruit and vegetables,” they said.

“That said, data from our study suggests that owning a cat during pregnancy or in early childhood does not pose a direct risk for offspring having psychotic symptoms later in life.”

The study did not investigate why apparently perfectly normal adults can suddenly change behaviours after acquiring a kitten or cat, such as posting endless photos and videos on social media sites, talking about “kittehz” and “hoomans”, and taking their unimpressed companion animals for photos with Santa.

Maria Hawthorne

(*disclosure – the author has two cats…. but the Editor is a dog person and insists no such study necessary for dog owners.)


Published: 03 Mar 2017