Scientists are studying a connection between the parasite Toxoplasma gondii (one of our personal fav

Scientists are studying a connection between the parasite Toxoplasma gondii (one of our personal favorites!) and its effect on behavior, most specifically, how it seemingly makes rats less afraid of cats. This isn’t mind control—if when a rat sees a cat, it’s still going to run away in fear. But while rats typically avoid cat urine, those infected with toxoplasma gondii do not.  

According to Ars Technica:

“When trying to explain how Toxo produces this effect, [researcher Ajai Vyas] initially focused on the obvious: the parasite’s presence in the brain. When Toxo infects, it barricades itself in thick-walled cysts to evade the immune system, and these cysts can remain for decades in a few sites, including the brain. If Toxo forms cysts in specific parts of the brain, it could do something there to affect behavior. But so far, different studies have found cysts in many different locations with no obvious pattern to their distribution, so it’s unclear if cyst location can influence behavior.”

Toxo, as the parasite is sometimes called, is not only interesting because of its curious influence on the predatory relationship between cats and rats, but also because it can infect many kinds of animals, including a third of humans worldwide. To the average person, Toxo is about as dangerous as the flu, but it is also associated with disorders like schizophrenia. However, scientists warn that these associations should be taken with a grain of salt. While connections between Toxo and behavior are present, researchers disagree on exactly what its effects are, on rats, cats, and humans alike.

“The reality is that human behavior and mental illness are complex, and many of the Toxo studies are not standardized and have yet to be replicated. Toxo certainly doesn’t make it easy to do this work—there’s no good way to detect Toxo cysts in a living person, and the studies rely on correlations with Toxo antibody levels. But antibodies are a crude measure that don’t tell you about a number of things that could affect behavior, such as when the infection occurred or which strain of the parasite you’re infected with.”

Read more about the link between toxoplasma gondii and the mind at Ars Technica.