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'Intermittent Explosive Disorder' Grabs Attention
Last reviewed and revised October 24, 2012
By Michael Craig Miller, M.D.
Harvard Medical School
Just after the publication of a study about intermittent explosive disorder (IED) in June 2006, the political commentator John McLaughlin had it on the agenda for his weekly television show. He introduced the issue like this:
"Road rage drivers are not just angry. They're crazy. So says research from Harvard and from the University of Chicago. The new sickness is called intermittent explosive disorder or IED. IED sufferers have abnormal areas of the brain that are supposed to control anger. "
The panelists then exchanged some amused banter.
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What Is Intermittent Explosive Disorder?
A person with IED is not crazy. IED is a disorder of impulse control. This means that an individual has difficulty resisting aggressive urges. This results in angry outbursts and destructive behavior that is out of proportion to the situation. A person with IED might assault another person or damage property.
This disorder came to the attention of news media at the time because of a June, 2006 article in the Archives of General Psychiatry, quoted in the McLaughlin program.
Researchers from Harvard and the University of Chicago surveyed thousands of people and found that IED was more common than previously thought: More than 7% of the people had responded to situations with uncontrollable anger at some point in their life. (This means that IED affects as many as 16 million Americans.) Almost three-quarters of those had a history of attacking people when they were angry. They also found that the disorder starts early around age 14 in many cases starting before any other psychiatric problem becomes apparent.
And, by the way, that research does not say that people with this cluster of symptoms and behaviors are, as Mr. McLaughlin would have had it, "crazy."
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Violence Is Common
These new data remind us how widespread violence is. IED doesn't affect any one cultural or socioeconomic group more than another, although younger people are more susceptible than older people. Also there are a wide variety of causes and consequences, with genetics (heredity) and environmental factors contributing equally.
More than 80% of the people surveyed met the criteria for at least one other psychiatric disorders that fell into one of the following categories:
- Personality disorders (antisocial or borderline personality disorder)
- Mood disorders (major depression, bipolar disorder)
- Anxiety disorders (panic disorder, post-traumatic stress disorder)
- Psychotic disorders (schizophrenia)
- Substance abuse (alcohol, drugs)
- Other medical illnesses (dementia).
Most people with IED in this study did get mental health treatment at some point, but it was rarely specifically for their anger. If anger had become a focus of treatment early on, experts speculate, perhaps their later psychiatric troubles could have been prevented, or at least reduced.
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The Biology of Violence
The study of aggression and violent behavior can help us understand IED. Since all behavior including criminal behavior originates in the brain, neuroscientists have focused on studying the biology behind violence.
This has taught us that:
- The ups and downs of stress hormones influence aggressiveness. In people who are quick to feel threatened or frightened, stress hormone levels may rise rapidly. In this state of hyperarousal, adrenaline pumps, heart rate goes up, and the body is ready to fight. The violent outbursts of IED "road rage" or domestic violence may follow this biological pattern. This process may also occur in borderline personality disorder or depression.
- Many violent criminals actually have reduced stress responses, called hypoarousal by scientists doing this research. They have much lower than average emotional barriers to committing violence. Often cold-blooded, their violent behavior may be more premeditated rather than flaring up in response to provocation.
- Some people with brain injuries become aggressive, especially if the frontal or temporal lobes of the brain are damaged. These regions control impulses and regulate emotion.
- Similar brain problems may explain the aggressiveness seen in Alzheimer's disease and other forms of dementia.
- Aggression and violence sometimes arise in connection with a symptom, such as paranoid delusions in schizophrenia or the irritability of mania.
- Substances like alcohol can lead to violence by changing the brain regions that control emotion and impulses, or by triggering a hyperarousal state.
As scientists learn more about these mechanisms, they may more accurately define the nature of violence. With a better understanding of what causes the biology to go wrong, treatment will probably also improve and go beyond simplistic prescriptions such as "anger management."
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An Opportunity for Early Treatment
There are two key messages that come out of this new research:
- Violence is a condition that could be treatednt even when no other symptoms are obvious.
- Since violence is often the first symptom to appear, treating it early may help avoid later problems such as the destructive consequences of violence and the psychiatric disorders that may develop.
Significant violence should be treated as a medical problem like chest pain. If clinicians look for underlying brain disease or injury, mood or psychotic disorders, personality disorders or substance abuse, they can then treat those illnesses. This could reduce risk.
For people who have the "pure form" of intermittent explosive disorder, where no other mental disorders are found, the serotonin-boosting antidepressants (like Prozac and Zoloft) may reduce irritability and lengthen a short fuse.
Recognizing violence as a treatable problem can and should lead an individual to take more responsibility for violent actions rather than less. Using a national news platform to make amused comments based on a superficial understanding of the problem deprives people of help. But it also deprives all of us of the chance to reduce violence. As we gain a better understanding through science of how people lose control, we may laugh at them less and help them more.
Kessler RC, Coccaro EF, Fava M, Jaeger S, Jin R, Walters E. "The prevalence and correlates of DSM-IV intermittent explosive disorder in the National Comorbidity Survey Replication." Archives of General Psychiatry. Jun 2006;63(6):669-678.
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Michael Craig Miller, M.D. is the Editor in Chief of the Harvard Mental Health Letter. He is also associate physician at Beth Israel Deaconess Medical Center and assistant professor at Harvard Medical School. He has been practicing psychiatry for more than 25 years and teaches in the Harvard Longwood Psychiatry Residency Program.