No, Cat Poop Parasites Don't Give You Mental Illnesses


Robin Andrews

Science & Policy Writer

Cats don't drive you literally crazy after all. Evgeny_PM/Shutterstock

Cats are raging little lion-esque psychopaths, and for some time, it was thought that a common parasite that they tend to be infected with could turn humans a bit doolally too. A new study, however, has concluded that the “crazy cat lady”-like syndrome is a myth, and there’s no evidence to support it.

Named Toxoplasma gondii, this micro-monster has been shown to make mice more suicidal, causing them to seek out cat urine in order to get killed by our feline companions, which in turn allows them to be infected. Cats are the only hosts in which the parasite is able to reproduce, so they have evolved mind-controlling mechanisms in order to ensure they worm their way inside them.


Although infected humans – who catch the little beasties via ingested cat poop particles – have never been shown to suddenly have a prevalence for their peculiar pet’s pee, there has been some circumstantial evidence as of late that cat owners are likely to suffer from mental illnesses, including schizophrenia, in later life.

Up to 60 million US adults are infected with T. gondii, and although it can very rarely cause physical harm, there has never been any experimental proof that the parasite affects our neurological workings in any way. Nevertheless, the statistical association between cat owning and psychological afflictions remained, hovering in the background like an unsolved mystery.

This new piece of research, published in the journal Psychological Medicine, took another look at this bizarre correlation. The team from University College London looked at the lives of 4,500 kids from birth to the time they turned 18, and looked at their mental health and whether or not their house had cats in it.

Ultimately, they could find no correlation between mental illnesses and cat ownership whatsoever when taking into account all possible factors – socioeconomic background, additional pets other than cats, number of family members, marital status, child gender, educational background, ethnicity, and so on.


It appears that plenty of previous studies failed to take many of these other variables into account. Additionally, unlike this team’s longitudinal study – which repeatedly asked the children throughout their lives about their mental health – other studies tended to interview their subjects just once and ask them to recall their mental state from several years back.

These two key factors are likely to have biased the results of studies that appeared to show there was a correlation between mental problems and cat ownership.

“Pregnant women should continue to avoid handling soiled cat litter, given possible T. gondii exposure,” the team cautiously conclude in their study. However, their data “strongly indicates that cat ownership in pregnancy or early childhood does not confer an increased risk of later adolescent psychotic experiences.”

Myth busted.


[H/T: Popular Science]


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