Research Links Cats to Development Of Mental Illness

Cats: you generally love 'em or hate 'em. We all know someone who owns one or several.

In a potential blow to cat hoarders, new research on a parasite commonly carried by cats – Toxoplasma gondii – suggests that it can be linked to mental illness in owners, particularly schizophrenia.

T. gondii is fairly deceptive. It's been shown to alter the behaviour in mice, casing them to become "suicidal."

Mice have a keen sense of smell. This means whenever they can smell cat urine, they'll avoid it. If infected with T. gondii, however, they are not averse to it; in many cases, they actively wander towards the smell. This, as you might expect, leaves them exposed to cat predation. After a quick pounce and kill, the mouse – along with its piggybacking parasites – are ingested by the cat.

Cats are only the hosts wherein the parasite is able to sexually reproduce. After the parasite produces new eggs within the cat, they are expelled as it defecates. These eggs are able to last for many months in a variety of dry and temperate climates, ready to infect another warm-blooded host.

This can, unfortunately, include humans. The parasite can't reproduce within a human host but it can cause toxoplasmosis. Apart from being acutely dangerous to those infected during pregnancy or those with a weakened immune system, there has been little evidence indicating a negative effect on healthy, infected adult humans. This is despite the fact that in the U.S. alone over 60 million people may be infected, according to the Centers for Disease Control and Prevention (CDC).

This study, published in the journal Schizophrenia Research, examines whether the ownership of a cat during childhood is more common in families with members who went on to develop mental health disorders later on in life. The researchers state that two earlier studies came to this conclusion and, using an extensive survey, attempted to replicate the finding. They were successful, reinforcing the link between early cat ownership and later-life schizophrenia and other serious mental illnesses.

It's important to note that this study merely highlights an association, rather than saying T. gondii is responsible.

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