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Cat Parasite May Increase Risk of Suicide In Humans

An anonymous reader writes "Researchers at the University of Maryland analyzing meticulous data collected by Danish authorities have identified a positive correlation between suicides among women with infection with the fairly common parasite T. gondii. Carriers were 53 percent more likely to commit suicide in a sample of 45,000 Danish women monitored for over a decade (researchers believe that the same correlation likely exists for men). Increased susceptibility to schizophrenia and bipolar disorder was also discovered. The physiological mechanism has not been determined, although some speculation centers around changes to dopamine levels. Two intriguing aspects were noted: 1) human infection often (but not always) begins by exposure to cats carrying the parasite, for example, by changing an infected animal's litter; and 2) the parasite spreads itself by infecting the nervous system of rodents, causing them to become suicidally attracted to feline odors which will increase the likelihood of their hosts being eaten by cats, whose digestive tracts provide the preferred environment for parasite reproduction."

16 of 252 comments (clear)

  1. The chicken and egg problem all over again by pyzondar · · Score: 5, Interesting

    Do the crazy cat ladies have cats because they are crazy, or are they crazy because they have cats?

    1. Re:The chicken and egg problem all over again by sackbut · · Score: 5, Funny

      Do the crazy cat ladies have cats because they are crazy, or are they crazy because they have cats?

      The parasite also causes decreased sexual inhibition. Translation: It makes women sluttier. No corresponding effect was found in men. Of course, this effect isn't as widely documented for obvious political reasons...

      That is because in men there is no sexual inhibition to effect.

    2. Re:The chicken and egg problem all over again by Anonymous Coward · · Score: 5, Informative

      If you knew anything about these parasites, you would not write what you just did.

      Cats are carriers. Rodents are part of their life cycle. Rodents infected with these parasites tend to be "more brave", some even to the point of taunting a cat to attack them. The cat eats infected rodents, and the cycle of the parasite is complete as it returns to the soil and rodents pick it up once more.

      Humans are just unintended side show for the parasite, but since these affect behaviour in mice brains, it is not surprising these parasites affect human brains too.

      http://www.livescience.com/5631-zombie-ants-controlled-fungus.html

      Is another example of similar effects in non-mammals by other, yet similarly acting organisms.

      In a similar unrelated note, there are experiments that show even more bizarre behaviours, like effectively a "personality transplant" by a swap of gut bacteria cultures between two mice. One aggressive and another docile. Swap their gut cultures, and you swap their bahaviours!

      There is plenty of other research starting to appear in this area,
            http://www.sciencedaily.com/releases/2011/05/110517110315.htm

      So basically, how you eat may tell what you are/may become and your becteria and viruses play bigger part in your life than you can image.

    3. Re:The chicken and egg problem all over again by Anonymous Coward · · Score: 5, Funny

      That is because in men there is no sexual inhibition to effect.

      Sure there is. It's just that rather than being controlled by the brain, it's governed by an external organ known variously as a "wife," "girlfriend," or, in the case of Slashdotters, "mother."

  2. don't trust em by Anonymous Coward · · Score: 5, Funny

    sure, this looks like valid research, until you see the citations

    Resurch dun by Carnegie Meloncat Institute fellows:
    Hovercat
    Longcat
    Dunecat
    with speshul thx 2 cieling cat hoo make all tings possible

  3. Kill all cats. by SuricouRaven · · Score: 5, Insightful

    They are a menace to public health.

    That's what people would say if cats were ugly, anyway. But they are cute, so they are permitted to carry disease. Only ugly species are eligable for culling.

  4. Re:Terrorist Weapon? by Anonymous Coward · · Score: 5, Funny

    Emo music sales soar 10.000%.

  5. The Origin? by Insanity+Defense · · Score: 5, Funny

    The first stage in the evolution of the Gou'ald has begun.

  6. Re:Terrorist Weapon? by pyzondar · · Score: 5, Funny

    Lolcats, schrödinger's zombiecats, misfortune-bringers of doom, spreading of mind controlling suicide parasites.. I fear cats more than any quoran toting goofball out there. It is time for someone to do something.

  7. Re:So cats contract it by eating rodents... by PolygamousRanchKid+ · · Score: 5, Funny

    ...but it's still okay to eat cats, right?

    The article is about human infections, so you might want to avoid eating humans. If you get infected, it will lower the dopamine level in your brain, and then you will get hungry for . . . another human brain . . .

    . . . I think I just figured out how the Zombie Apocalypse thing will start . . .

    --
    Schroedinger's Brexit: The UK is both in and out of the EU at the same time!
  8. Correlation != causation by Anonymous Coward · · Score: 5, Interesting
    Exactly. Also:

    2) the parasite spreads itself by infecting the nervous system of rodents, causing them to become suicidally attracted to feline odors

    Suicidally? Being attracted to something known to shorten your lifespan doesn't mean you're suicidal. Take one example: Americans gorging themselves on McDonald's, then flooding hospitals with heart disease cases in an attempt to stay alive. If they were suicidal, they'd just keep eating more burgers and look emo about it till they died.

  9. Re:Zombie Virus by Anonymous Coward · · Score: 5, Funny

    You mean "purr-fect" this virus, eh?

  10. Interesting topic, poor summary by Harvey+Manfrenjenson · · Score: 5, Interesting

    The Danish study is just the latest in a long series of studies which demonstrate a correlation between toxoplasmosis seropositivity and psychiatric problems-- it's been linked to schizophrenia and ADHD, and so on. Wikipedia has a good article on the topic.

    It's pretty interesting. Apparently something like 10% of the US population is seropositive for toxo. The infection is thought to be "contained" immunologically, but encysted organisms are still present in muscle and nervous tissue, and the process of "containment" may induce a subtle inflammatory state which affects a broad variety of neurotransmitters (not just dopamine). It's also possible that the causation works the other way-- the people who get chronic infections may have something about their immune system that is different to begin with, and the difference might predispose them to psychiatric problems independently of toxo infection. Good discussion of all that in the Danish study, which was published in Archives of General Psych and seems to be non-paywalled.

    What will be really interesting is to see what happens if you identify psychiatric patients with chronic toxo and try to eradicate the toxo with antibiotics-- do their psych symptoms improve? There have been at least two studies I could find (one where it helped and one where it didn't), and apparently there's a large-scale study getting started in the UK.

  11. Control group by phantomfive · · Score: 5, Interesting

    For people who are wondering, it looks like they didn't have a good control group. So here is how they answered some potential objections:

    1) What if depressed people get cats, and that's why they have the parasite? Did they check people who have cats but aren't depressed?
    It's probably not related to cats, because most people who get this parasite get it from undercooked meat.

    2) What if depressed people are more susceptible to this parasite because they are depressed? What if non-depressed people are capable of fighting off the parasite with a stronger immune system?
    There was no correlation between people who had the parasite, and people who had a history of mental illness. (Also, correlates with other studies, that might have had better control groups, I'm too lazy to check them out to see).

    --
    "First they came for the slanderers and i said nothing."
  12. Re:Terrorist Weapon? by Anonymous Coward · · Score: 5, Funny

    As it should be. Now if we could start pushing the one true Imperial unit system. Keep the faith brothers.

  13. Re:So cats contract it by eating rodents... by tehcyder · · Score: 5, Funny

    Wash your hands.

    If you are a cat owner, and you can't handle the simple fact that you are dealing with feces and vomit every day without a proper hygiene protocol, something has already gone wrong.

    I've got cats and I don't handle their feces every day. I let my neighbourds do that when the cats go and crap in their rosebeds.

    --
    To have a right to do a thing is not at all the same as to be right in doing it