The protozoan made me do it!

While I don’t have all day to study it in detail, I found this Atlantic article (“How Your Cat Is Making You Crazy“) deeply absorbing. A scientist has spent many years researching the psychological effects of human infection by the common protozoal agent Toxoplasma gondii, transmitted primarily by the house cat. He claims to have studied infected versus uninfected humans in detail, and documented distinct personality differences:

…30 to 40 percent of Czechs had the latent form of the disease, so plenty of students were available “to serve as very cheap experimental animals.” He began by giving them and their parasite-free peers standardized personality tests—an inexpensive, if somewhat crude, method of measuring differences between the groups. In addition, he used a computer-based test to assess the reaction times of participants, who were instructed to press a button as soon as a white square popped up anywhere against the dark background of the monitor.

The subjects who tested positive for the parasite had significantly delayed reaction times. Flegr was especially surprised to learn, though, that the protozoan appeared to cause many sex-specific changes in personality. Compared with uninfected men, males who had the parasite were more introverted, suspicious, oblivious to other people’s opinions of them, and inclined to disregard rules. Infected women, on the other hand, presented in exactly the opposite way: they were more outgoing, trusting, image-conscious, and rule-abiding than uninfected women.

The findings were so bizarre that Flegr initially assumed his data must be flawed. So he tested other groups—civilian and military populations. Again, the same results. Then, in search of more corroborating evidence, he brought subjects in for further observation and a battery of tests, in which they were rated by someone ignorant of their infection status. To assess whether participants valued the opinions of others, the rater judged how well dressed they appeared to be. As a measure of gregariousness, participants were asked about the number of friends they’d interacted with over the past two weeks. To test whether they were prone to being suspicious, they were asked, among other things, to drink an unidentified liquid.

The results meshed well with the questionnaire findings. Compared with uninfected people of the same sex, infected men were more likely to wear rumpled old clothes; infected women tended to be more meticulously attired, many showing up for the study in expensive, designer-brand clothing. Infected men tended to have fewer friends, while infected women tended to have more. And when it came to downing the mystery fluid, reports Flegr, “the infected males were much more hesitant than uninfected men. They wanted to know why they had to do it. Would it harm them?” In contrast, the infected women were the most trusting of all subjects. “They just did what they were told,” he says.

Why men and women reacted so differently to the parasite still mystified him. After consulting the psychological literature, he started to suspect that heightened anxiety might be the common denominator underlying their responses. When under emotional strain, he read, women seek solace through social bonding and nurturing. In the lingo of psychologists, they’re inclined to “tend and befriend.” Anxious men, on the other hand, typically respond by withdrawing and becoming hostile or antisocial. Perhaps he was looking at flip sides of the same coin.

There’s a lot more, and not surprisingly, driving is affected too. (Better not let the busybody insurance companies know about this, or they’ll raise the rates on cat owners. And cat haters might claim that cats have killed more people than dogs!)

I’m a natural born skeptic, but I try to keep an open mind, and thus I am not happy to admit that the researcher’s thesis might just have merit. I had heard about T. gondii but I am ashamed to admit that I had not known about the way the disease benefits the cat by reprogramming the brains of rodents. This has been documented for years, and is even noted in the Wiki entry:

T. gondii infections have the ability to change the behavior of rats and mice, making them drawn to, rather than fearful of, the scent of cats. This effect is advantageous to the parasite, which will be able to sexually reproduce if its host is eaten by a cat.^[12] The infection is highly precise, as it does not affect a rat’s other fears such as the fear of open spaces or of unfamiliar-smelling food.

Studies have also shown behavioral changes in humans, including slower reaction times and a sixfold increased risk of traffic accidents among infected, RhD-negative males,^[13] as well as links to schizophrenia including hallucinations and reckless behavior. Recent epidemiologic studies by Stanley Medical Research Institute and Johns Hopkins University Medical Center indicate that infectious agents may contribute to some cases of schizophrenia.^[14][15] A study of 191 young women in 1999 reported higher intelligence and lower guilt proneness in Toxoplasma-positive subjects.^[16]

I almost feel like having myself tested, simply out of morbid curiosity. Not that there is any cure, and not that I can do anything about it, but if I thought that my personality was being influenced by a protozoan, well, it helps to know these things. The more information we have, the better. Seriously, if I consider my anxious and introverted nature, might I not be better off being able to blame a protozoan than to blame myself?

What’s even more fascinating is the possibility that this is the tip of the iceberg. There could be a whole host of personality changing organisms. I mean, just look at some of the things that happen in nature:

Consider Polysphincta gutfreundi, a parasitic wasp that grabs hold of an orb spider and attaches a tiny egg to its belly. A wormlike larva emerges from the egg, and then releases chemicals that prompt the spider to abandon weaving its familiar spiral web and instead spin its silk thread into a special pattern that will hold the cocoon in which the larva matures. The “possessed” spider even crochets a specific geometric design in the net, camouflaging the cocoon from the wasp’s predators.

OK, OK, I’m… considering. And I don’t especially like it. Who knows what organisms may be possessing us, influencing us, and even making us do things without our knowledge? Seriously, this sort of thing belongs in science fiction. To think that this is all happening according to the Laws of Nature and Nature’s God is deeply disturbing.

Should I be worried? Nah. Not only am I a morbidly reckless fatalist, but I’m allergic to cats. And besides, I have been around dogs for so long that I’m probably infected with another organism that prevents me from being influenced by the cat organism.

But sometimes I worry that Coco is acting too much like a cat.

AFTERTHOUGHT: This organism has infected 10 to 20 percent of Americans. And while there has been little more than a collective “ho hum” to that, I find myself having to ask a rhetorical question.

Would there be more public outcry if a potentially brain-influencing infection were transmitted sexually?

And if so, how rational is that?