For ages, cat people have desperately trying to shake the personal of, well, being crazy cat people. Do they sometimes wear sweaters with cats on them? Sure. Do they read Cat Fancy cover-to-cover? Perhaps. Are they possibly being driven toward schizophreniaand other forms of mental illness by their beloved felines? Possibly, according to one biologist, and several studies.

According to a profile in the March issue of The Atlantic, bizarrely-coifed Art Garfunkel-look-alike and Czech biologistJaroslav Flegr is hot on the Case of the Crazy Cat People. His research onToxoplasma gondii, the parasite in question, began back in the 90s, based on his own experience. Initially, he was decried as kind of a quack for theorizing that parasites harbored in cat poop was making people act weird (yeah, that does sound like a strange claim), but in the last decade or so, the idea has actually started to garner quite a bit of support.

Toxoplasma gondiihas already been identified as dangerous in some cases–it causes Toxoplasmosis, which can be extremely harmful to unborn fetuses. But the idea that it may alter the brain is something new.

The first wave of buzz built on Flegr's theory wasstarted in 2006,when a study ofToxoplasma gondii found that it could, potentially, impact everything from brain function to behavior. Since then, scientists have continued to probe the topic, slowly releasing study after study, these parasites have now been linked to obsessive-compulsive behavior (like the kind that leads to pet-hoarding), friendliness, and yes, schizophrenia.

Hosts may not even realize thatToxoplasma gondii has infiltrated their body. That's because a lot of the time, it just sort of nests (by creating a little hole in a cell to live), and doesn't even alert the host's immune system. But how does that potentially change the way pet owners act?

Jaroslav Flegr (the ginger scientist who started this all) thinks the change in behavior in humans is possible, because it's been seen in rats that have been infected. To sexually reproduce, the parasite needs to get back into the cat, because it can't actually reproduce anywhere other than a cat's stomach. So the parasite changes the way the rat thinks about cats by moving into the rat's brain and limiting the rat's inhibitions–allowing a cat to get close, eat the rat, and then, hopefully, become re-infected. And so, speculates Flegr, the parasite will do what it does in rats, which can lead to reckless behavior.

That these feline parasites might impact human behavior isn't that crazy of an idea–you've heard of "cat scratch fever," right? And other parasites behave similarly–the flatworm, for example, is known to do this. But of course, that doesn't exactly mean that just because your neighbor treats Mimi, Fifi, Sprinkles, and Tinkerbell like they're her children, she's certifiably off her rocker.

It does, however, mean that the hangers-on that hang around the litter box may need to be treated with more sensitivity than previously thought. Because the parasite has been indirectly transmitted to humans in a shocking volume: as much as half the population of the planet may have been infected with it at some point.

The take-away message? Use gloves and caution when cleaning up the kitty litter and, if your cat's got a kicking problem, consider an enclosed space for her to do what she has to do. And if you start to feel the urge to adopt 40 more just like her, consider seeing a professional.

Want more information? This RadioLab episodeon the subject is highly enlightening.

Images: Thinkstock and the Simpsons Wiki