Toxoplasmosis May Be Linked To 'Crazy Cat Lady' Syndrome As It Alters Brain And Behavior
We all either know someone (or are that someone) with a reputation for showing some feline love. This person is stereotyped to be an eccentric, scatterbrained woman, popularly dubbed the "crazy cat lady." We understand the love, but what about the crazy? Turns out there may be a scientific explanation behind the nutty reputation.
In TED-Ed's latest video, “Is There A Disease That Makes Us Love Cats?” host Jaap de Rood explains the cat disease — toxoplasma gondii (T. gondii or Toxo for short) — can influence the behavior and brain activity of cats, rats, and mammals, including humans. Toxoplasmosis is caused by T. gondii, a parasite that is excreted by cats in their feces, and the reason pregnant women are told to avoid cats' litter boxes. Doctors believe a woman who becomes infected during pregnancy is able to transmit the disease to the fetus, which could potentially result in severe brain damage or early death.
The parasite lives at the expense of its host, meaning it needs the host in order to produce offspring, known as "oocysts." Oocysts are shed in the cat's feces, with a single cat able to shed up to 100 million oocysts.
If a mouse accidentally ingests the offspring, they will invade the mouse's tissues and mature to form tissue cysts. However, if the mouse gets eaten by a cat, the tissue cysts become active and release offspring to make new oocysts — completing the cycle.
These parasites invade white blood cells to “hitch a ride” to the brain, where they seem to override the innate fear of predators. For example, infected rodents are more reckless and have slower reactions. Ironically, they're attracted to feline urine, which probably makes them more likely to cross paths with a cat, and help the parasite complete its lifecycle.
Today, about a third of the world's population is infected with toxoplasma, and most of them don't even know it. In healthy people, physical symptoms often don't show up at all, and if they do, they're mild and flu-like. The parasites can mess with the brain too. Several studies have found connections between Toxo and schizophrenia, bipolar disorder, OCD, and aggression. The parasite can also slow reactions and decrease concentration, which may explain why people who get in traffic accidents are three times more likely to have gotten toxoplasma.
Cats aren’t the only ones that can infect humans with oocysts. Contaminated water, unwashed produce, and playing in sandboxes pose risks too. Eating undercooked meat from other animals that pick up oocysts is another way humans can ingest it.
So, is Toxo the reason many people love cats? Possibly. The science is still 50/50.
The crazy thing? You and your cat are just two hosts of Toxo among the billions in the world.