Intermittent Explosive Disorder
A disorder of impulsive aggression has been included in DSM since the first edition. In DSM-III, this disorder was codified as Intermittent Explosive Disorder (IED) and was thought to be rare. However, DSM criteria for IED were poorly operationalized and empiric research in IED was limited until the past decade, when research criteria were first developed.1 Subsequently, interest in disorders of impulsive aggression led to a series of epidemiological studies that documented IED to be as common as several other psychiatric disorders.
Other recent research indicates that criteria for IED best identifies a group of individuals with robust differences in clinical characteristics, neurobiological findings, and documented responsiveness to treatment. In addition, other data strongly suggest important delimitation from other disorders previously thought to obscure the diagnostic uniqueness of IED. These data, across many studies by a variety of investigators, led to newly revised criteria for IED in DSM-5.
What is impulsive aggression?
Human aggression constitutes a multidetermined act that results in physical (or verbal) injury to self, others, or things. It appears in several forms and may be defensive, premeditated (predatory), or impulsive (nonpremeditated). When recurrent in frequency, the latter two forms are psychopathological. A converging pattern of data consistently points to critical differences between impulsive and premeditated aggression such that while the two may appear in the same individual at different times, the underpinnings of the two are quite different.2,3
Because this article is confined to IED as defined in DSM-5, the focus is on impulsive aggression. The most critical aspect of this phenomenon is that acts of impulsive aggression represent a quick and typically angry response nearly always triggered by a social threat or frustration that is out of proportion to the situation. These aggressive acts may include verbal arguments, temper tantrums (with or without property damage or harm to others), property assault, or assault on people or animals. In fact, the severity of the aggressive outburst is less relevant than the fact that the aggressive behavior is “explosive.” Other important DSM-5 criteria specify that most of the aggressive outbursts are impulsive, cause distress to the individual or impairment in the psychosocial function of the individual, and are not due to another disorder (ie, do not occur exclusively during another disorder).
Epidemiology of IED
The National Comorbidity Survey Replication (NCS-R) reported a lifetime prevalence of IED in the US of 7.3% by “broad [DSM-IV] criteria” and 5.4% by “narrow criteria,” and past year prevalence of 3.9% and 2.7%, respectively.4 Inspection of the data reveals meaningful differences between the two IED types, with “narrow” IED being far more severe than “broad” IED.5 “Broad” IED stipulates only 3 aggressive outbursts during a lifetime; “narrow” IED requires at least 3 aggressive outbursts in a year.
DSM-5 criteria include both non-injurious and non-destructive aggressive outbursts, provided that they are quite frequent (ie, average of 2 outbursts per week for at least 3 months). The number of DSM-5 IEDs in the US is uncertain; however, a review of the raw data from the NCS-R study suggests that the lifetime prevalence of DSM-5 IED is likely to be between 2% and 3%.
Because impulsive aggressive behavior appears in patients with many diagnoses, most clinicians have been reluctant to make a diagnosis of IED in the absence of other psychiatric diagnoses. In fact, impulsive aggressive behavior is manifest in all humans early in life and before the onset of other psychiatric disorders. In the vast majority of people, impulsive aggressive behaviors diminish over time, frequently well before adolescence.6 In the adolescent supplement to the NCS-R, lifetime prevalence of DSM-IV IED by “narrow” criteria was 5.3%, similar to what was found in adults.7
Clinical studies suggest significant comorbidity of IED with mood disorders, anxiety disorders, and substance use disorders. In each case, with the exception of phobic anxiety disorders, the age of onset of IED is reported to be earlier than that of the comorbid disorder. This suggests independence of the disorders or that IED might be a risk factor for the comorbid disorder. A similar finding was found in a family history study of IED.8 Some argue that the diagnosis of IED should not be made in the presence of borderline personality disorder (BPD) or antisocial personality disorder (ASPD). However, when examined empirically, levels of lifetime aggressive behavior among “BPD/ASPD only” individuals are markedly lower than those among persons who also meet criteria for IED, indicating that both diagnoses should be made when criteria for both are met.1
There has been evidence for the association between impulsive aggression, and/or irritability, and cardiovascular morbidity for many years. A reanalysis of a large community data set has confirmed this relationship for DSM-IV IED.9 Specifically, the study noted that in individuals with IED, there is an increased risk of coronary heart disease; hypertension; stroke; diabetes; arthritis; ulcer; headaches; and back/neck pain and other chronic pain. Another study reports a significant correlation between IED and diabetes.10
Intermittent Explosive Disorder
March 25, 2015 | Special Reports, Neuropsychiatry, Trauma And Violence
By Emil F. Coccaro, MD
Linked Articlesbetween IED and diabetes.10