Toxo “Hype Train” Running Out of Steam?

Recent research is challenging the “conventional wisdom” that infection with the Toxoplasma gondii parasite can alter human behavior, lead to mental illness (especially schizophrenia). As a recent post on Discover magazine’s Neuroskeptic blog notes, “The idea of ‘behavioral’ toxoplasmosis has driven a huge amount of research and media interest.”

Of course, it’s also driven the witch-hunt against outdoor cats—used by the American Bird Conservancy and others in their ongoing campaign of misinformation and scaremongering.

But, reports Neuroskeptic, a new paper published in PLoS ONE suggests “that there may be nothing to worry about after all. [Its authors] report that toxoplasmosis is associated with essentially no behavioral abnormalities in humans.”

The post, “The Myth of ‘Mind-Altering Parasite’ Toxoplasma Gondii?,” summarizes the research very well, and is structured in a way that makes it quite reader-friendly. No need to cover the same ground here, then. Instead, I’d like to comment briefly on the paper itself, in which Duke University’s Karen Sugden and her co-authors report:

“Our results suggest that a positive test for T. gondii antibodies does not result in increased susceptibility to neuropsychiatric disorders, poor impulse control or impaired neurocognitive ability. Moreover, we found no association between seropositivity and aberrant personality functions.”

One explanation for their “null findings,” according to the authors: “earlier reports of links between T. gondii infection and behavioral impairments are exaggerated.” [1] “Exaggerated” is being too kind, I think, at least in those cases that border of retraction-worthy sloppiness. Still, the point is an important one, and long overdue.

Whether or not this research attracts much attention remains to be seen. I wish I could say I was optimistic. Unfortunately, such “negative” results provide little fuel for the “hype train around this media-friendly microbe,” to borrow a phrase from Neuroskeptic.

Literature Cited

1. Sugden, K., et al., Is Toxoplasma Gondii Infection Related to Brain and Behavior Impairments in Humans? Evidence from a Population-Representative Birth Cohort. PLoS ONE, 2016. 11(2): p. e0148435.