Scientists Now Say Owning A Cat Might Cause Mental Illness And The Evidence Is Scary

Breaking news: cats can drive you crazy. Alright, so maybe that’s late-breaking news, but anyone with a cat can testify that their feline’s furniture-scratching and late-night energy bursts can be enough to trigger more than a few headaches.

However, recent studies show that owning cats can have a very real effect on our brains. Scientific evidence suggests there’s a reason to be especially careful when cleaning out your cat’s litter box. Your sanity just might depend on it…

If you’ve ever lain awake at night, staring at the ceiling while your cat is bouncing off the walls, then it shouldn’t come as a surprise when people say your feline friend will drive you crazy. But did you know the problem might be more serious than you think?

Allyson Hicks

Recent studies reveal there is evidence linking cats to human craziness in more than just the metaphorical sense. That’s right: your precious kitty could actually be driving you bonkers, but you’ll be surprised to learn why…

野貓王 / Flickr

Apparently, it’s not just the nighttime crazies that cats are prone to that have their owners losing their minds. Rather, there’s something specific that cats carry that affects our brain chemistry…

The Times of Chester County

The real culprit in question is a micro-organism known as Toxoplasma gondii (or T. gondii). This bacteria is present in cat urine, and cat lovers may come into contact with it regularly! As if you needed another reason to be grossed out by the litter box…

Tom Thai / Flickr

Still, avoiding T. gondii requires more than just washing your hands after scooping cat litter. In fact, according to a 2016 article in the New York Times, as many as 11 percent of Americans had “dormant Toxoplasma cysts in their brains.” Yikes.

Chris Warren / Flickr

Luckily, having T. gondii  in your bloodstream isn’t enough to send you over the edge—a healthy immune system keeps adverse effects at bay. Still, cat owners aren’t totally out of the woods when it comes to this bacteria…

Kaushal Vaidya / Flickr

To fully understand the proposed link between T. gondii and human craziness, you have to look at the function of the bacteria, the way it has evolved over the years, and how cats have even used it to their advantage!


T. gondii is spread when a cat consumes something contaminated with the bacteria, which then reproduces in its digestive system. It’s passed through urine and feces, which then infects other animals—namely, rats.

The Spruce

Studies show that rats that have been infected with T. gondii actually lose their sense of fear toward cats. Astonishing? Yes. And it gets even weirder than that, if you can believe it…

Max Pixel

Rats who don’t fear cats won’t run away from them. This means the cat gets an easy meal… and the bacteria is passed on to a new host, where the cycle continues. There are even further connections to the bacteria and how it affects humans, though.


After recognizing how the T. gondii bacteria affected rats’ brains, scientists took their research one step further: they looked at how the bacteria affected chimpanzees, the closest human ancestor.

Nosilla ogra / Wikimedia

For this part of the study, researchers didn’t use house cat urine like they had for the rats. Instead, Clémence Poirotte, an evolutionary biologist in Montpellier, France, dabbed drops of leopard and human urine on a fence enclosing 33 test apes to see what would happen…

So, what did they find? Chimpanzees infected with the T. gondii started sniffing the leopard urine much more than those not infected with it. They were actually attracted to the urine with this bacteria!

KaaSatha / DeviantArt

Of course, scientists wouldn’t declare this definitive proof that T. gondii was eliminating the life-preserving “fear instinct” in chimps, but it certainly raised some interesting questions…

Pierre-Hadrien Pottier / The Verge

If T. gondii was capable of making chimps less afraid of the things that could kill them, was it possible the bacteria could have the same effect on humans, as well? Are T. gondii infections that are passed on from house cats responsible for “creating” daredevils?

NY Daily News

A 2015 edition of the Journal of Psychiatric Research asserted that humans infected with the bacteria were more prone to impulse or aggression. So it could, in fact, be the reason some of us are risk-takers!

justinclayton99 / Flickr

Other research suggests links between T. gondii  and some unfortunate events: Though the numbers were negligible, the study found people with infections attempted suicide more often than those without. Of course, correlation doesn’t always indicate causation.

Duke Unversity

Moreover, a recent study published in a 2015 edition of Schizophrenia Research suggested a connection between people who had been exposed to cats from a young age and the development of mental illness later in life.


Still, it’s worth it to note that the scientific community hasn’t drawn any definitive conclusions, and it’s currently engaged in a spirited debate over whether this evidence is conclusive or just a coincidence…

maiu maiu / Flickr

In the end, no research suggests holding off on getting a new kitty because it might make you crazy. After all, cats—like many pets—offer many benefits, such as companionship. Still, you may want to be thorough when you wash your hands after scooping out the litter box… just in case!

Mikael Moiner / Flickr

Remember: the next time you’re losing sleep over your noisy nocturnal cat, at least he isn’t literally messing with your mind. No word yet on whether that’s enough to keep people from calling you a “crazy cat lady,” though!

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