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New theory links cat parasite to schizophrenia

 (Photo by Junko Kimura/Getty Images)
(Photo by Junko Kimura/Getty Images)
Junko Kimura/Getty Images

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The well worn phrase "crazy cat lady" has finally received some scientific validation. Kathleen McAuliffe joins the show to discuss her article, "How your cat is making you crazy", which appears in the March issue of The Atlantic.

McAuliffe profiles Jaroslav Flegr, a Czech scientist operating in relative obscurity, who claims that he has isolated a parasite found in cats that can alters brain circuits. The parasite "T. Gondii" causes cysts in the brain and disconnects circuits like a "microscopic puppeteer," affecting such emotions as fear, anxiety and sexual arousal. Initial tests on rats showed that infected test subjects exhibited decreased fear of cats, a condition called "Feline Fatal Attraction."

And Flegr claims that these brain alterations can have significant affects on human behavioral patterns. Infected men acted "introverted, suspicious, oblivious to other people’s opinions...and [were] inclined to disregard rules" while infected women "were more outgoing, trusting, image-conscious, and rule-abiding than uninfected women."

Two large studies conducted by Flegr also show that those who tested positive for T. Gondii were "two and a half times as likely to be in a traffic accident as their uninfected peers." Other findings border on the bizarre. For instance, he found that infected men responded more to the smell of cat urine, leading him to consider it a possible aphrodisiac for infected men.

But Flegr is quick to acknowledge that the parasite is unlikely to cause full scale personality transformations, and he is wary of directly linking specific personality traits to the parasite. However, for a small amount of people, the parasite could be extremely dangerous. Regarding his most recent research, he says, "[it] suggests the parasite may trigger schizophrenia in genetically susceptible people.” His conclusions stem from the decreased amount of gray matter in the brain of schizophrenic subjects - a decrease which occurred almost exclusively in those infected with T. Gondii.

The seemingly outlandish theory has drawn some considerable praise from some heavy hitting peers, such as Stanford’s Robert Sapolsky, who has vocally endorsed Flegr's methodology. Other studies such as those of parisitologist Joanne Webster have confirmed similar findings regarding the effects of parasites on neurotransmitters controlling dopamine levels.

But don't go throwing out your cats quite yet, because as McAuliffe discovered, only outdoor cats carry T. Gondii and they only shed it for three weeks of their life.


Kathleen McAuliffe is the author of the article, "How your cat is making you crazy," which appears in the March issue of The Atlantic.