People suffering from intermittent explosive disorder, a psychiatric condition characterized by recurrent spells of sudden and extreme rage, are more than twice as likely to have been exposed to a common parasite, researchers from the University of Chicago report in a new study.
Writing in Wednesday’s edition of the Journal of Clinical Psychiatry, the researchers explained that a study involving 358 adult subjects found a link between the disorder and toxoplasmosis, a typically harmless parasitic infection carried by nearly one-third of all men and women.
“Our work suggests that latent infection with the toxoplasma gondii parasite may change the brain chemistry in a fashion that increases the risk of aggressive behavior,” senior study author Dr. Emil Coccaro, a professor and the chair of Psychiatry and Behavioral Neuroscience at the university, explained in a statement.
“However, we do not know if this relationship is causal, and not everyone that tests positive for toxoplasmosis will have aggression issues,” he added, noting that additional research is required.
As many as 16 million Americans are believed to have IED, an ailment marked by recurrent, impulsive, and problematic outbursts of physical or verbal aggression disproportionate to the situations that bring them on, the study authors explained.
Findings could lead to new treatment options for IED
The new study is part of the Chicago-led team’s efforts to improve the diagnosis and treatment of the condition, and investigated IED’s possible association to toxoplasmosis, a common parasitic infection transmitted through the feces of infected cats, contaminated water or undercooked meat that is ordinarily latent and harmless in the majority of healthy adults.
However, the condition is known to reside in brain tissue and had previously been linked to such psychological disorders as schizophrenia and bipolar disorder. Dr. Coccaro’s team recruited 358 US adults and evaluated them for IED, personality disorder, depression and other conditions, and scored them on trails such as anger, aggression and impulsiveness as well.
Nearly one-third of the subjects had IED, while another third were diagnosed with another kind of psychiatric disorder and the remaining one-third were healthy subjects with no history of such conditions. Compared to the healthy control group, the IED group were more than twice as likely (22 percent to 9 percent) to test positive for toxoplasmosis exposure, the researchers said.
Sixteen percent of the group with non-IED disorders also tested positive for toxoplasmosis, but were found to have aggression and impulsiveness scores similar to the control group. Members of the IED group scored far higher on those measures than either of the other two groups. Across all three groups, toxoplasmosis-positive subjects scored “significantly” higher when it comes to anger and aggression, the university said in a statement.
Dr. Coccaro said that he and his fellow researchers are now further examining the potential link between toxoplasmosis, aggression and IED. He said that it will require “experimental studies to see if treating a latent toxoplasmosis infection with medication reduces aggressiveness. If we can learn more, it could provide rationale to treat IED in toxoplasmosis-positive patients by first treating the latent infection.”
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Image credit: David Ferguson
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