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Rebekah Eliason for redOrbit.com – Your Universe Online
According to a study with nearly 200 participants, people with intermittent explosive disorder (IED) possess elevated amounts of two markers of systemic inflammation in their blood. IED is a psychiatric illness characterized by impulsivity, hostility and recurrent aggressive outbursts.
This study is the first of its kind and is carefully controlled to document the direct relationship between inflammatory markers and recurrent, problematic, impulsive aggression in people diagnosed with IED, but not people with good mental health or with other psychiatric disorders.
“These two markers consistently correlate with aggression and impulsivity but not with other psychiatric problems,” said senior study author Emil Coccaro, MD, the Ellen C. Manning professor and chairman of the Department of Psychiatry and Behavioral Neuroscience at the University of Chicago. “We don’t yet know if the inflammation triggers aggression or aggressive feelings set off inflammation, but it’s a powerful indication that the two are biologically connected, and a damaging combination.”
This disorder of impulsive aggression, including outbursts such as “road rage,” is disruptive to the lives of those with IED along with their family, friends and colleagues. People suffering from IED are prone to overreact during stressful situations by bouts of uncontrollable anger and rage.
Often the IED outbursts are out of proportion to the level of stressors that trigger them. At first, the angry blow-ups may be explained away by friends as “simply bad behavior,” Coccaro said, “But intermittent explosive disorder goes beyond that. It has strong genetic and biomedical underpinnings. This is a serious mental health condition that can and should be treated.”
Along with causing professional and social difficulty, IED is known to predispose people to other mental illnesses including, depression, anxiety and alcohol or drug abuse. According to a 2010 study, people with IED also have an increased risk for certain other health issues such as coronary heart disease, hypertension, stroke, diabetes, arthritis, ulcers, headaches and chronic pain.
IED is a common disorder found in 2006 by Coccaro and colleagues to affect up to five percent of adults, approximately 16 million Americans. Usually, episodes start in males during adolescence around age thirteen and at age nineteen for females.
In this study, researchers focused their efforts on two markers, C-reactive protein (CRP and interleukin-6 (IL-6), which cause inflammation in blood levels. Each protein has previously been associated with impulsive aggressive behaviors in humans, cats and mice.
In response to an infection or injury, the liver will produce CRP. This is designed to help focus the immune system towards dead or damaged cells. The other marker, IL-6 is secreted by white blood cells in an effort to stimulate immune responses of fever and inflammation. When IL-6 is produced, it also increases the production of CRP.
Participants included 197 physically healthy volunteers who were measured for CRP and IL-6 levels. Of the subjects, 69 had been diagnosed with IED, 61 had psychiatric disorders not involving aggression and 67 did not have any psychiatric disorder.
On average, both the CRP and IL-6 levels were higher in participants with IED when compared to both psychiatric and normal controls. For example, the average CRP levels were double for those with IED than in normal healthy volunteers. Both types of markers were significantly elevated in subjects with the strongest background of aggressive behaviors. Since each marker independently correlated with aggression, the authors noted this suggested that “both have unique relations with aggression.”
Previous studies have indicated there are connections between inflammatory response and depression or stress, said Coccaro. In healthy people, exposure to endotoxins, which set off powerful immune reactions, there is a much higher brain reaction to social threat exposure such as photographs of an angry or fearful face than people who were not exposed to the endotoxin.
In summary, the discoveries reported in the new paper suggest that “medications that reduce inflammation may also drive down aggression,” Coccaro said.
Celebrex or aspirin, which are anti-inflammatories, may make a difference for people with IED. As the treatments available are only able to put less than 50 percent of patients into remission, the authors said that “Additional strategies for the examination and intervention of human impulsive aggression are needed.”
This study was published December 18, 2013 in JAMA Psychiatry.