Título:
Common Parasite Linked to
Personality Changes
Eating a raw steak or owning a cat can make
you more outgoing
By Tori Rodriguez
Fecha: Septiembre 24,2012
Fuente:
scientificamerican (PUNTO) com/article (PUNTO) cfm?id=common-parasite-linked-to-personality-changes
Feeling
sociable or reckless? You might have toxoplasmosis, an infection caused by the
microscopic parasite Toxoplasma gondii, which the CDC estimates has
infected about 22.5 percent of Americans older than 12 years old. Researchers
tested participants for T. gondii infection and had them complete a
personality questionnaire. They found that both men and women infected with T.
gondii were more extroverted and less conscientious than the infection-free
participants. These changes are thought to result from the parasite's influence
on brain chemicals, the scientists write in the May/June issue of the European
Journal of Personality.
“Toxoplasma
manipulates the behavior of its animal host by increasing the concentration of
dopamine and by changing levels of certain hormones,” says study author
Jaroslav Flegr of Charles University in Prague, Czech Republic.
Although
humans can carry the parasite, its life cycle must play out in cats and
rodents. Infected mice and rats lose their fear of cats, increasing the chance
they will be eaten, so that the parasite can then reproduce in a cat's body and
spread through its feces [see “Protozoa Could Be Controlling Your Brain,” by
Christof Koch, Consciousness Redux; Scientific American Mind, May/June 2011].
In
humans, T. gondii's effects are more subtle; the infected population has
a slightly higher rate of traffic accidents, studies have shown, and people
with schizophrenia have higher rates of infection—but until recent years, the
parasite was not thought to affect most people's daily lives.
In
the new study, a pattern appeared in infected men: the longer they had been
infected, the less conscientious they were. This correlation supports the
researchers' hypothe-sis that the personality changes are a result of the
parasite, rather than personality influencing the risk of infection. Past
studies that used outdated personality surveys also found that toxoplasmosis-related
personality changes increased with the length of infection.
T.
gondii is most commonly contracted through
exposure to undercooked contaminated meat (the rates of infection in France are
much higher than in the U.S.), unwashed fruits or vegetables from contaminated
soil, and tainted cat litter. The parasite is the reason pregnant women are
advised not to clean litter boxes: T. gondii can do much more damage to
the fetal brain than the personality tweak it inflicts on adults.
This article was originally published with
the title Common Parasite Linked to Personality Changes.
Fuente:
scientificamerican (PUNTO) com/article (PUNTO) cfm?id=common-parasite-linked-to-personality-changes
