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."

Comments

Re:The chicken and egg problem all over again

[Anonymous Coward]

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.

Re:So cats contract it by eating rodents...

[fustakrakich]

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

will?

a better explanation of the study

[WiPEOUT]

http://www.nursingtimes.net/home/clinical-specialisms/infection-control/cat-ladies-suicide-risk-probed/5046843.article?blocktitle=Behind-the-Headlines&contentID=4530

Re:a better explanation of the study

[Anonymous Coward]

And the effect size is moderate. But the actual risk in absolute number terms for any given individual remains small, and the trumps the other data. The linked discussion in Nursing Times makes clear that the study was not well controlled. It also points out that there are multiple potential sources of toxoplasmosis infection, most of which are considerably more common ways of getting the infection than handling cats. So, no reason to put kitty to sleep just yet.

Re:Terrorist Weapon?

[Baloroth]

SI standards specify that a period (or a comma, for that matter, the proper indicator is a space), should not be used for digit grouping, which means the "American" interpretation is actually the internationally accepted scientific/engineering standard.