A new study conducted at the University of Chicago shows an association between the Toxoplasma gondii parasite and road rage, or Intermittent Explosive Disorder (IED). The disorder is characterized by explosive bouts of uncontrollable rage.
Pet cats are known to pass the parasite along to humans by shedding the T. gondii eggs in their feces. Cat owners can pick up the parasite when cleaning litter boxes without washing their hands thoroughly. This increases the chance of unintentionally ingesting the eggs from unwashed hands.
In felines, the parasite normally resides in the gastrointestinal tract. However, when humans and other warm-blooded animals ingest the parasite, it uses leukocytes, or white blood cells, to travel from the intestine to other organs, finally localizing in muscle and brain. Once T. gondii reaches the brain, it hides within neurons and glial cells, forming cysts.
In adults with active, healthy immune systems, the parasite causes no problems and is relatively harmless, but according to the study, “latent toxoplasmosis has been linked to several psychiatric disorders (eg, schizophrenia, bipolar disorder, personality disorders) and with suicidal behavior.”
The research involved 358 subjects, including a control group of 110 subjects with no evidence of psychiatric illness. The researchers found that of the subjects diagnosed with IED, 22 percent tested positive for toxoplasmosis exposure, compared to 9 percent of the control group.
“Not everyone that tests positive for toxoplasmosis will have aggression issues,” said research leader Dr. Emil Coccaro of the University of Chicago. However, exposure to the parasite does appear to “raise the risk for aggressive behavior.”
While the study suggests a relationship between toxoplasmosis and aggression, study co-author Royce Lee, associate professor of psychiatry and behavioral neuroscience says there is no need to get rid of your cat. “We don’t understand the mechanisms involved—it could be an increased inflammatory response, direct brain modulation by the parasite, or even reverse causation where aggressive individuals tend to have more cats or eat more undercooked meat. Our study signals the need for more research and more evidence in humans.”
There have been numerous studies on Toxoplasma gondii, including one in 2014 that suggested that the parasite could be used in fighting certain types of cancer. In 2012, Digital Journal reported on a study that showed women infected with the parasite had an increased risk of attempting suicide.
This interesting study, “Toxoplasma gondii Infection: Relationship With Aggression in Psychiatric Subjects,” was published in the March 2016 issue of The Journal of Clinical Psychiatry.
