July 26, 2013
By Michael Craig Miller M.D.
Harvard Medical School
Under severe enough stress, any normally calm and collected person might become angry, even to the point of violence. But some people lose their temper repeatedly — tension mounts until there is an explosive release.
Since the early 1980s, this type of repetitive behavior has been called intermittent explosive disorder (IED). People with this disorder respond with strong rage that is out of proportion to the situation. They may cause serious harm to people and property through violent words or deeds.
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A Controversial, but Common Problem
IED is more common than experts initially believed, and it can be quite destructive. A community survey by the National Institute of Mental Health showed that 5% to 7% of people have the symptom at some point during their lifetime. At any given time, 3% to 4% have the disorder. It also found that people with IED were often young, with the disorder starting in the early teens. The majority were male.
In the severest cases (at least three rage attacks per year), a person with IED may have dozens of episodes over time, leading to injuries requiring medical attention or causing thousands of dollars in property damage.
The condition remains controversial, especially when it is diagnosed in an individual being held to account for violent actions. Some commentators have worried that the diagnosis could be used as an "excuse" for bad behavior.
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The Causes Are Uncertain
We have limited information about the causes of IED, but we do know the disorder affects people in all cultural and socioeconomic groups.
It is sometimes hard to tell the difference between IED and other disorders that feature impulsive, aggressive behavior, including personality disorders, mood disorders, anxiety disorders and substance abuse.
Because all behavior originates in the brain, neuroscientists have focused on studying the biology behind violence. And given the high cost of IED to perpetrators and their victims, each new insight into the biology of this disorder is of great interest. Here's what we know so far:
- Close relatives of IED patients appear to have a significantly elevated risk of IED.
- Several studies suggest that the disorder is associated with abnormal activity in parts of the brain responsible for regulating, even inhibiting, aggressive behavior. The chemical messenger involved is serotonin.
- Impulsive aggression, in general, is associated with low serotonin activity. Such aggression is also linked to damage to the prefrontal cortex, a center of judgment and self-control in the very front of the brain. One study found that, on some neuropsychological tests, people with IED performed similarly to patients who had suffered damage to the prefrontal cortex.
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Treatment Can Help
People who have trouble resisting their violent impulses, no matter what the cause, are not very likely to seek treatment. This is the biggest challenge for mental health professionals. Also, family and friends may be uncomfortable approaching a person with a violent temper to suggest getting help.
Many people with IED have had some psychiatric treatment, but fewer than 20% have been treated specifically for their impulsive rage attacks, according to 2 surveys. Those who do receive treatment often wait a decade or more after symptoms start to seek help. Often this is after significant violence has occurred or because they are seeking treatment for a different disorder.
Research on drug treatment has been limited. A number of medications are known to reduce aggression and prevent rage outbursts:
- Antidepressants, especially selective serotonin reuptake inhibitors (SSRIs)
- Mood stabilizers (lithium and antiseizure drugs)
- Antipsychotic drugs
In one study, impulsively aggressive patients who took the SSRI fluoxetine (Prozac) showed increased activity in the prefrontal cortex. Another study found that those who took fluoxetine for 12 weeks experienced statistically significant reductions in impulsive aggressive behavior compared with those who took a placebo. Researchers cautioned that even though the effect appeared strong, fewer than half the patients taking fluoxetine achieved a full or partial remission.
Cognitive behavioral therapy (CBT) combines cognitive restructuring, coping skills training and relaxation training. This approach looks promising for treating IED.
One small study looked at group and individual CBT. After 12 weekly sessions, patients participating in either individual or group therapy were significantly less aggressive and angry, and less depressed, than those in a control group. Those who attended individual therapy sessions also reported an improvement in their overall quality of life. Three months later, the improvements persisted.
Although we continue to need more research on treatment for IED, studies continue to support the idea that violence can be treated, even when no other symptoms are present. In fact, with many patients, violence may be the only symptom for a long time before any other problem appears. Early treatment can lower the risk to patients and their potential victims.
To read more about this topic, see Mental Illness and Violence or Intermittent Explosive Disorder Grabs Attention.
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Michael Craig Miller, M.D., is Senior Editor of Mental Health Publishing at Harvard Health Publications. He is an assistant professor of psychiatry at Harvard Medical School. Dr. Miller is in clinical practice at Beth Israel Deaconess Medical Center, where he has been on staff for more than 25 years.