Pet Cats Could be Causing People to Become Mentally Ill


Ongoing research continues to indicate a connection between our domestic feline friends and mental illness in humans – especially schizophrenia.

The most recent study, published in the journal Schizophrenia Research, set out to learn whether owning a cat while in childhood predisposes a person to developing mental health disorders. Researchers were attempting to replicate the findings of two previous studies that had come to that conclusion. And they succeeded, adding more weight to the argument in favor of cause and effect.

The factor at work appears to be the parasite Toxoplasma gondii, commonly carried by cats – the only hosts in which it’s able to reproduce itself on.

After the parasite produces new eggs, they are expelled as the animal defecates. They can last for many months in a variety of dry and temperate climates. Although humans are not viable hosts, we can develop toxoplasmosis, which can cause miscarriage and fetal problems in pregnant women and is acutely dangerous to anyone whose immune system is weakened. Other effects can be long-lasting illness similar to the flu, blindness and even death. The Centers for Disease Control (CDC) estimates that more than 60 million people in the US may be victims.

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This latest study makes only a circumstantial case for the relationship between the parasite and mental illness, as no firm proof yet exists. But the team looked at 50 peer-reviewed studies showing that individuals infected with the Toxoplasma gondii parasite were nearly twice as likely to develop schizophrenia later in life.

And evidence exists that antipsychotic drugs, commonly used to treat patients with schizophrenia, tend to negate the effects of toxoplasmosis in both rats and humans. That may be further indication of a link, but studies are inconclusive on that point.

Various other studies conducted in the past have documented links between Toxoplasma gondii infection and subtle changes in behavior such as increased levels of dopamine, extroversion in females (and introversion in males), and increased inhibition in risky or frightening situations. The infection has been cited as doubling the infected person’s risk of getting into a car accident by slowing reaction times. The condition is sometimes referred to as the “crazy cat lady syndrome.”

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Our outside pets pick up the parasite from infected rodents or birds while hunting or by contact with the feces of an infected cat, says the ASPCA. If they stay in the house, chances of them getting it are greatly reduced.

E. Fuller Torrey, of the Stanley Medical Research Institute, adds: “Cats kept exclusively indoors are quite safe. For outdoor cats, pregnant women should not change the litter box and children’s sandboxes should be covered at all times when not in use.”

If your cat must go out, be sure to clean the litter box every day, change the liner and – as a further precaution -be sure to wear gloves while doing it and wash your hands thoroughly afterward.