I can’t stop thinking about an article I read in the Atlantic last year. It’s about a Czech biologist named Jaroslav Flegr who theorized that his brain was being affected by parasites carried by his pet cat. Sounds pretty far-fetched, right? Flegr believed that an organism known as T. Gondii, which causes toxoplasmosis, might be affecting unsuspecting cat owners at alarming rates. The article is wonderful and I highly recommend it, but it’s a very long read, so I thought I’d summarize some of the most interesting points here.
Pre-Flegr, the standard wisdom held that T. Gondii was only dangerous to a few classes of people. For almost 100 years, doctors have known that it poses a risk to unborn fetuses, which is why pregnant women are warned to stay away from cat litter boxes. It also affects people with weakened immune systems, and can cause dementia in people at the end stages of AIDS. In healthy people, however, T. Gondii just causes some minor flu-like symptoms for a short time, although it does remain in the brain cells, inactive.
But is it truly inactive? Flegr says no. Citing his own extensive T. Gondii research, and tales of dozens of other bizarre parasites that exist out there and wreak havoc on animals’ brains, he makes a compelling case that as many as one-third of all humans on earth might be unknowingly hosting a toxic parasite that is messing with their minds.
Some of Flegr’s early studies surprised him so much that he assumed the data was flawed, but he was able to reproduce the results again and again. Looking at the 30-40% of people who have this latent form of T. Gondii lurking in their brains, he noticed slowed reaction times and even differences in personality. He also noticed that the brains of men and women showed different–sometimes completely opposite–brain changes related to the T. Gondii. For example, the men who were T. Gondii carriers were more suspicious and introverted than uninfected men, while the infected women were more open and extroverted than uninfected women.
The evidence that T. Gondii affects the human brains is reasonably strong, but many people still aren’t convinced. Flegr teamed up with a scientist from Charles University and they found that brain scans of people with schizophrenia and T. Gondii showed decreased gray matter compared with people who had schizophrenia but no T. Gondii. Some Turkish scientists (not affiliated with Flegr) have found that people with T. Gondii are involved in a higher rate of traffic accidents. And the seriousness and breadth of the research is mounting. Students working in the lab of Stanford’s famed stress researcher Dr. Robert Sapolsky published a study about T. Gondii’s effect on fear circuits in the brain (it disables them.) Researchers from Imperial College London and the University of Leeds have found that in rats, T. Gondii is concentrated in pleasure centers of the brain and can set dopamine production out of whack.
I’m pretty surprised that this research doesn’t get more press and interest from the media and the general public. This is potentially groundbreaking stuff! Of course, more studies are needed to prove causality beyond correlation, but if 30-40% of all people may be affected in even a subtle way, the effects of T. Gondii on the human brain might deserve a bit more of our collective attention.
In the meantime, I’m going to recommend that all my cat-loving friends amp up their brain training regimen at BrainHQ, just in case.
If you want to learn more, I recommend you read the full article from the Atlantic.