Intermittent explosive disorder: Taming temper tantrums in the volatile, impulsive adult
More-inclusive diagnostic criteria acknowledge the true prevalence of this aggression disorder, and a new algorithm suggests a two-pronged treatment approach.
Diagnostic exclusionary criteria were modified so that individuals with:
- antisocial or borderline personality disorder could be diagnosed with IED if otherwise warranted
- aggressive behaviors confined within major depression episodes could not be diagnosed with IED.
This last change recognized that impulsive, aggressive outbursts could point to major depressive disorder.
When the revised criteria were tested in patients seeking treatment for aggression, those who met IED-R criteria were found to exhibit significantly greater aggression and impulsivity (using validated scales) and lower global functioning than those who did not.7 Statistical adjustments made to account for aggression score differences eliminated the difference in global functioning, which suggested a direct link between aggression and global function in individuals with IED-R.
Two patterns. Later research uncovered at least patterns of aggressive outbursts:
- low intensity at high frequency (such as verbal arguments or door slamming approximately twice weekly)
- high intensity at low frequency (such as physical aggression resulting in injury or destruction of nontrivial property at least three times per year).
Data revealed that 69% of individuals with IED-like histories displayed both aggression patterns, 20% displayed only the high-intensity/low-frequency pattern, and 11% displayed only the low-intensity/high-frequency pattern.
Because further analysis revealed no important differences between these groups in measures of aggression and impulsivity, IED-R criteria were revised to include both patterns in the “A” criteria. This revision integrated the essences of IED-R and DSM criteria into one diagnostic set (Table 2).
INFLUENCE OF HEREDITY
No twin or adoption studies of IED have been performed. However, family history data suggest that IED (or IED-type behavior) is familial. I recently conducted a blinded, controlled, family history study using IED-R criteria and found a significantly elevated risk for IED (p < 0.01) in relatives of persons with a history of IED (26%), compared with non-IED controls (8%). Comorbid conditions did not affect the risk among the IED subjects or their relatives, suggesting that IED is familial and independent of other conditions.13
Nearly all studies of aggression’s biology and treatment have measured aggression as a dimensional variable along a continuous scale from low to high.14 Our studies have allowed us to explore biological and treatment response correlates. In preliminary analyses, we have found that the maximal prolactin response to d-fenfluramine challenge and the number of platelet serotonin transporter binding sites are:
- reduced in subjects meeting research criteria for IED
- inversely correlated with dimensional measures of impulsive aggression.
Table 2
Updated diagnostic criteria for intermittent explosive disorder
| A. Recurrent incidents of aggression manifest as either: |
| 1. Verbal or physical aggression towards other people, animals, or property occurring twice weekly on average for 1 month |
| OR |
| 2. Three episodes involving physical assault against other people or destruction of property over a 1-year period |
| B. The degree of aggressiveness expressed is grossly out of proportion to the provocation or any precipitating psychosocial stressors |
| C. The aggressive behavior is generally not premeditated (ie, is impulsive) and is not committed to achieve a tangible objective (such as money, power, intimidation, etc.) |
| D. The aggressive behavior causes marked distress in the individual or impairs occupational or interpersonal functioning |
| E. The aggressive behavior is not better explained by another mental disorder (such as a major depressive/manic/psychotic disorder, attention-deficit/hyperactivity disorder, general medical condition [head trauma, Alzheimer’s disease], or due to the direct physiologic effects of a substance) |
| Source: Adapted from reference 7 |
Earlier, Virkkunen et al15 reported reduced cerebrospinal fluid 5-hydroxyindoleacetic acid concentrations in persons diagnosed with IED based on DSM-III criteria, compared with persons who were not diagnosed with IED and those who demonstrated nonimpulsive aggression.
TREATING IED
Cognitive therapy. Few double-blind, randomized, placebo-controlled trials of any treatments for IED have been published. Trials using cognitive-behavioral approaches have reduced self-rated anger and its expression in young adults with anger disorders.16 Although many of these subjects may have had IED, it is not known if this approach works in IED.
Table 3
Characteristic behaviors of aggressive individuals*
| Severity | Behaviors |
|---|---|
| Mildly aggressive | Occasional verbal arguments and/or temper tantrums |
| Moderately aggressive | Frequent verbal arguments and temper tantrums (about twice weekly on average), occasional destruction of property, rare or occasional physical assault against others (usually without injury) |
| Highly aggressive | Frequent verbal arguments and temper tantrums (about twice weekly) and/or more than occasional destruction of property or physical assault against others, sometimes with injury |
| * Characteristics given are descriptive and not based on data. | |
Drug therapy. SSRIs. A trial by this author using fluoxetine showed that impulsive aggressive behavior responds to treatment that targets the central serotonergic system.12 Forty subjects with personality disorders and histories of impulsive aggression received fluoxetine, 20 to 60 mg qd, or placebo for 12 weeks. Fluoxetine reduced overt aggression and irritability about 67% more than placebo, as assessed by the Overt Aggression Scale Modified for Outpatients (OAS-M).
