"and the worms eat into your brain"

I mentioned toxoplasmosa the other day, and now there's a Straight Dope about it! Plate. Shrimp. Plate-o-shrimp.

Here's where things get strange. While the link between toxoplasmosis and birth defects has long been recognized, scientists now suspect that T. gondii may cause schizophrenia too. That in itself represents a major change in thinking -- till recently the assumption, based on twin studies and the like, has been that schizophrenia is transmitted genetically. No way, scoffers say: schizophrenia is so profoundly disabling that sufferers tend not to reproduce. Germs are a likelier candidate. Studies typically have found T. gondii antibodies occurring in schizophrenics at twice the rate seen in control groups.

But get this. Forty-five percent of schizophrenics tested positive in one study for both T. gondii and LSD. To quote a recent paper: "These results support the hypothesis that T. gondii may cause schizophrenia and may do so by producing or triggering the production of an hallucinogenic chemical." [...] "Production of such a compound may have been favored by natural selection because an infected, hallucinating rodent would be more easily captured by a cat." In other words, schizophrenia in humans may be a side effect of T. gondii's attempt to set cats up with a steady supply of tripping mice, the better to ensure its own reproductive success.

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43 Responses:

  1. kraquehaus says:

    I am going to change my moniker from T.bias to T.gondii

  2. strspn says:

    Apparently this is no longer controversial: Cecil's source; independent confirmations by experimental replication: 1, 2, 3, 4, and indirect corroboration. Wow.

  3. mooflyfoof says:

    Maybe I'm reading that wrong, but are they suggesting that T. gondii produces the chemical LSD in the brain? What about the more obvious answer, that a schizophrenic had taken LSD at one point in their life, and that--perhaps in conjunction with the T. gondii--triggered it? Or are those just urban legends? (i.e. that LSD stays in the system permanently and that schizophrenia can be brought about by taking LSD)

    • leolo says:

      "can be brought about" is pretty vague.

      Latent schizophrenia can be exacerbated by LSD, this I've witnessed. Created by LSD, I doubt is possible.

      • mooflyfoof says:

        I don't know the details, it was just something I'd heard-- hence the vagueness. :) But yeah, that's about what I meant, that latent schizophrenia can be exacerbated by LSD. What if "latent schizophrenia" is really "mom got toxoplasmosis when I was in the womb"? Hmm. What I was really getting at, though, was that I didn't understand why the scientists are assuming that LSD in the brain of schizophrenics when there's also T. gondii antibodies means that the T. gondii is creating the LSD. It seems like the more likely answer is that the people took LSD and that's why it's in their system-- especially since it's apparently been shown that LSD can "exacerbate latent schizophrenia".

        • leolo says:

          A guess : LSD has an estimated half-life of 175 minutes (~3 hours). So unless all those schizos are regularly taking LSD (doubtful) there has to be another source.

        • denshi says:

          It's not that implausible -- lsd is a tryptamine, same as serotonin, melatonin, and a bunch of other neurotransmitters, and a bunch more psychoactive compounds, many of which are closer to the natural forms than is LSD. Your brain is working with similar chemical machinery for the production and receptivity of all of them, and there is some evidence that the brain produces some psychedelics at varying times for yet unknown purposes (I theorize that your brain trips balls on its own schedule).

          • deeptape says:

            There was a great presentation on a LSD rat study at the Basel conference week before last. Come over tomorrow afternoon to watch the DVD!

          • lars_larsen says:

            DMT is produced in the brain during sleep, its probably related to dreaming. If there is a drug, there is usually an endogenous system that goes with it. For example, schizophrenics have a low level of anandamide, which is the body's natural ligand for the THC receptor.

            • denshi says:

              Do you have a link to that research? I've read some stuff on endogenous DMT, but haven't seen any research yet that conclusively proves its production.

              • lars_larsen says:

                Wish I did. I've read papers that it exists naturally in the brain, but cant dig them up right now. The rest is pure speculation.

      • lars_larsen says:

        "Dont give crazy people LSD" is a good rule of thumb.

      • ethernight says:

        "Latent schizophrenia can be exacerbated by LSD, this I've witnessed."

        What do you mean when you say you've witnessed this? Do you mean that you've done scientific research on the matter, or known someone who has taken LSD and at some point later their latent schizophrenia surfaced, or became more pronounced?

        If you mean the former, I would be very interested in this research. Last I heard, while it's tough to gather research on the subject, that statistical analysis did not show a coorelation between rise in use of LSD and rise of schizophrenics, as would be expected if the theory correct.

        If you mean the latter - well, I can see how that would make quite an impact. However I don't tend to put a lot of stock in anecdotal evidence, personally.

        • leolo says:

          Unfortunately, closer to the latter. Friend took LSD. Was checked into a psych ward later that day. 10 years on, he's still there.

          • ethernight says:

            "Unfortunately, closer to the latter. Friend took LSD. Was checked into a psych ward later that day. 10 years on, he's still there."

            That is indeed unfortunate. I'm sorry to hear that.

    • lars_larsen says:

      LSD isnt very stable, its out of your body in 30 minutes or so actually. It just leaves a wake of destruction in your brain for several hours after.

      LSD causes insanity in those who haven't taken it. :)

  4. irma_vep says:

    Wow. That is interesting. Maybe that explains why in folklore, cats are viewed as evil.

  5. qzee says:

    "No way, scoffers say: schizophrenia is so profoundly disabling that sufferers tend not to reproduce." this is an overgeneralization, quite a few schizophrenics are as able to manage day to day life as anyone else, they do have children. Their siblings have children. Now, while this does not necessarily mean that schizophrenia is genetic or inheritable,it does not remove the possibility that genetics play a role.

    Also, the link you mention has not been proven beyond a shadow of a doubt and it has less proof supporting it than the genetic link.

    • denshi says:

      See also: contributing factors.

    • rsheridan6 says:

      ..meaning a mutation that is beneficial when you have it in genes from one parent, but harmful when you have it in both chromosomes.

      See http://www.guardian.co.uk/frontpage/story/0,16518,1653778,00.html for an explanation of why schizophrenia genes may be adaptive.

      I would like to hear what the "scoffers" have to say about Tay-Sachs disease, which is genetic and kills its victims as toddlers.

      • cnoocy says:

        IIRC, Tay-Sachs carriers (people with only one gene for it) have a resistance to tuberculosis, which has kept the mutation alive in the populace. Also, there is a late-onset form, which could (though in practice probably doesn't) allow victims to have children.

    • boonedog says:

      I've known a handful of people who's mothers are/were schizophrenic. So, inability to function has apparently not dissuaded many people from having children. In fact, if you think about it, crack addicts, homeless women, complete drunks, bedridden and depressed people have children ... the non-functioning aspect doesn't seem to have anything to do with whether or not people procreate.

  6. hallerlake says:

    It's the cats! They're poisoning our precious bodily fluids

  7. felicks says:

    That rules and I fucking love the Straight Dope,

  8. romulusnr says:

    Production of such a compound may have been favored by natural selection because an infected, hallucinating rodent would be more easily captured by a cat.

    proxy evolution is bullshit. I don't buy it. A tends to have X because that makes B stronger. But that makes A weaker, which means A will die out, depriving B of X. Unless B is deliberately doing something to promote A and/or X, there's no causation. Eating A with X doesn't do that.

    I think it was invented by the Discovery Institute to debunk evolution.

    This comment was brought to you by the letters W, T, and F.

    • jwz says:

      I see your point, but I think what they're saying is more like "B and X are ganging up on A", that is, "cats and T. gondii are conspiring against rats." A symbiotic relationship between cats and T. gondii, even though T. gondii is physically in the rat, not the cat.

    • strangehours says:

      Lets imagine that there exist two strains of T.gondii, one of which causes rodents to be more susceptible to predation, and one which doesn't. Also, lets assume that cats aren't on the verge of driving rodents to extinction. Obviously this will lead to the former strain being transmitted to cats with a higher frequency, and lead to higher rates of transmission back to rodents due to a greater proability that cat faeces will contain the former strain of T.gondii.

      Another example of the same variety: malaria induces behavioural changes in infected mosquitoes and also acts to make hosts more attractive to mosquitos at the point at which a blood meal would be most infective to the mosquito.

      I can't see why you think this doesn't constitute a selective advantage.

  9. baconmonkey says:

    ahh, toxoplasma, is there anything you can't do?