Intermittent explosive disorder

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Intermittent explosive disorder

Everyone has heard of road rage or read newspaper stories about a usually calm and responsible person who “snaps” and commits a violent act. Some people lose their tempers in this way repeatedly and dramatically, causing serious emotional or physical harm to themselves and others. It’s a pattern in which tension builds until an explosion brings relief, followed eventually by regret, embarrassment, or guilt.

Since the early 2000s, research has been shedding more light on this condition, now called intermittent explosive disorder. It is defined by attacks of impulsive rage that seem out of proportion to the immediate provocation and have serious consequences — verbal abuse, threats, property damage, assaults, and injuries. The American Psychiatric Association’s definition includes all such behavior that can’t be better explained by a diagnosis of antisocial or borderline personality, attention deficit disorder, conduct disorder, substance abuse, or dementia.

Research has been showing that intermittent explosive disorder is more common and more destructive than anyone had supposed. One study of several hundred people in the Baltimore area found that a surprising 11% had qualified for the diagnosis at some time in their lives, and 3% for current diagnosis. These percentages were about the same for men and women, blacks and whites. Only age made a difference: Younger people were more susceptible.

In a study of 1,300 psychiatric outpatients in the Providence, Rhode Island, area, the lifetime incidence was nearly 15%. In this study, younger, less educated and black or Hispanic patients were found to be more susceptible. Symptoms first appeared on average six years earlier in men (age 13) than in women (age 19).

Among the 6,000 participants in the National Comorbidity Survey Replication, a community survey by the National Institute of Mental Health, the lifetime incidence ranged from 5% to 7% and the current prevalence from 3% to 4%, depending on how strictly the condition was defined. People with more severe cases (at least three rage attacks in one year) averaged 56 lifetime attacks resulting in an average of $1,600 worth of property damage and 23 incidents in which someone required medical attention. In this study, people with intermittent explosive disorder were more likely to be young and slightly more likely to be male. The vast majority, as in other studies, were diagnosed with at least one other disorder, the most common being generalized anxiety, alcohol abuse, and attention deficit disorder. Intermittent explosive disorder apparently raises the risk for other psychiatric conditions by increasing chronic stress.

What causes the attacks? Several studies suggest that they are associated with abnormal activity of the neurotransmitter serotonin. Impulsive aggression in general is associated with low serotonin activity as well as damage to the prefrontal cortex, a center of judgment and self-control. One study found that on some neuropsychological tests, people with intermittent explosive disorder performed similarly to patients who had suffered damage to the prefrontal cortex. Another study found abnormal EEG (brain wave) activity in response to rapidly changing patterns or flashes of light in young people who had episodes of explosive anger. More specific information is needed about the triggers of rage attacks, and especially about the connection with drug and alcohol abuse.

Researchers have been exploring what may be a biologically significant distinction between “hyperarousal-driven” aggression — uncontrollable outbursts of the kind that occur in intermittent explosive disorder — and “hypoarousal-driven” or cold-blooded aggression, usually self-aggrandizing and associated with other kinds of antisocial behavior. Animal studies suggest that hyperarousal-driven aggression is associated with excessive stress hormone responses and hypoarousal-driven aggression with the opposite.

Although many people with intermittent explosive disorder have had some psychiatric treatment, few of them have been treated specifically for their impulsive rage attacks — fewer than 20% in the Baltimore and Providence surveys. This suggests that mental health professionals need to be more aware of the problem.

Drug treatment of intermittent explosive disorder has not been studied much, but a number of medications are known to reduce aggression and prevent rage outbursts, including antidepressants, mood stabilizers (lithium and anticonvulsants), and antipsychotic drugs. In one study, impulsively aggressive patients who took the antidepressant fluoxetine (Prozac) showed increased activity in the prefrontal cortex.

Cognitive behavioral therapies may also help. Anger management through a combination of cognitive restructuring, coping skills training, and relaxation training looks promising. And because intermittent explosive disorder often begins in early adolescence, school-based violence prevention programs may offer some hope.

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Last updated:	August 22, 2006