The trait of impulsivity has been the subject of ongoing interest in psychiatry and the very concept is still in flux. Impulsivity is a defining characteristic of many psychiatric illnesses, even those not classified as ICDs. Examples of these are borderline personality disorder, conduct disorder, binge-eating disorder, among many others.

Impulsivity is the failure to resist an impulse, drive, or temptation that is potentially harmful to oneself or others and is a common clinical problem and a core feature of human behavior. An impulse is rash and lacks deliberation. It may be sudden and ephemeral, or a steady rise in tension that may reach a climax in an explosive expression of the impulse, which may result in careless actions without regard to the consequences to self or others. Impulsivity is evidenced behaviorally as an underestimated sense of harm, carelessness, extroversion, impatience, including the inability to delay gratification, and a tendency toward risk-taking and sensation-seeking. What makes an impulse pathological is the person’s inability to resist it and its expression.

22.3.1 Diagnostic Features

Intermittent explosive disorder (IED) is a DSM diagnosis used to describe people with pathologic impulsive aggression. Impulsive aggression, however, is not specific to IED. It is a key feature of several psychiatric disorders and and may emerge during the course of yet other psychiatric disorders. Therefore, IED as formulated in DSM-IV-TR is essentially a diagnosis of exclusion.

The individual may describe the aggressive episodes as “spells” or “attacks.” The symptoms appear within minutes to hours and, regardless of the duration of the episode, may remit almost as quickly. As in other ICDs, the explosive behavior may be preceded by a sense of tension or arousal and is followed immediately by a sense of relief or release of tension.

Although not explicitly stated in the DSM-IV-TR definition of IED, impulsive aggressive behavior may have many motivations that are not meant to be included within this diagnosis. IED should not be diagnosed when the purpose of the aggression is monetary gain, vengeance, self-defense, social dominance, or expressing a political statement or when it occurs as a part of gang behavior. Typically, the aggressive behavior is ego-dystonic to individuals with IED, who feel genuinely upset, remorseful, regretful, bewildered, or embarrassed about their impulsive aggressive acts.

In one very small study, most of the subjects diagnosed with IED identified their spouse, lover, or girl/boy friend as a provocateur of their violent episodes. Only one was provoked by a stranger. For most, the reactions occurred immediately and without a noticeable prodromal period. All subjects with IED denied that they intended the outburst to occur in advance. Most subjects remained well-oriented during the outbursts, although two claimed to lose track of where they were. None lost control of urine or bowel function during the episode. Subjects reported various degrees of subjective feelings of behavioral dyscontrol. Only four felt that they completely lost control. Six had good recollection of the event afterward, eight had partial recollection, and one lost memory of the event afterward. Most IED subjects tried to help or comfort the victim afterward.

22.3.2 Epidemiology

Little is known about the epidemiology of intermittent explosive disorder. Historically it has been thought uncommon, but the National Comorbidity Survey Replication (NCS-R) study found that IED is much more common than previously thought. Lifetime and 12-month prevalence estimates of DSM-IV-defined IED were 7.3% and 3.9%, with a mean 43 lifetime attacks. IED-related injuries occurred 180 times per 100 lifetime cases. Mean age at onset was 14 years.

22.3.3 Assessment and Differential Diagnoses

The differential diagnosis of IED covers the differential diagnosis of impulsivity and aggressive behavior in general. The DSM-IV-TR diagnosis of IED is essentially a diagnosis of exclusion, and the clinician should evaluate and carefully rule out more common diagnoses that are associated with impulsive violence. For example, a careful history and attention to detail may help to distinguish IED from conditions such as antisocial personality disorder (ASPD) or borderline personality disorder (BPD). Patients with IED are usually genuinely distressed by their impulsive aggressive outbursts and may voluntarily seek psychiatric help to control them. In contrast, patients with ASPD do not feel true remorse for their actions and view them as a problem only insofar as they suffer their consequences, such as incarceration and fines. Although patients with BPD, like those with IED, are often distressed by their impulsive actions, the rapid development of intense and unstable transference toward the clinician during the evaluation period of patients with BPD may be helpful in distinguishing it from IED.

Other causes of episodic impulsive aggression are substance-use disorders, in particular alcohol abuse and intoxication. When the episodic impulsive aggression is associated only with intoxication, IED is ruled out. However, IED and alcohol abuse may be related, and the diagnosis of one should lead the clinician to search for the other.

Neurologic conditions such as dementias, focal frontal lesions, partial complex seizures, and post-concussion syndrome after recent head trauma may all present as episodic impulsive aggression and need to be differentiated from IED. Other neurologic causes of impulsive aggression include encephalitis, brain abscess, normal-pressure hydrocephalus, subarachnoid hemorrhage, and stroke. In these instances, the diagnosis would be personality change due to a general medical condition, aggressive type, and it may be made with a careful history and the characteristic physical and laboratory findings.

22.3.4 Comorbidity

Subjects with IED most frequently have other Axis I and II disorders. The most frequent Axis I diagnoses comorbid with IED include mood, anxiety, substance, eating, and other ICDs ranging in frequency from 7% to 89%. Such Axis I comorbidity rates raise the question of whether IED constitutes a separate disorder. However, recent data finding earlier onset of IED compared with all disorders, except for phobic-type anxiety disorders, suggest that IED is not secondary to these other disorders. Individuals with IED may have comorbid mood disorders. Although the diagnosis of a manic episode excludes IED, the evidence for serotonergic abnormalities in both major depressive disorder and ICDs supports the clinical observation that impulsive aggression may be increased in depressed patients, leading ultimately to completed suicide.

22.3.5 Course

Limited research is available concerning the age at onset and natural course of IED. But, according to DSM IV-TR and anecdotal case reports, the onset appears to be from childhood to the early twenties, and may be abrupt and without a prodromal period. The age of onset and course of IED distinguish it as separate from its comorbid diagnoses. The course of IED is variable, with an episodic course in some and a more chronic course in others. IED may persist well into middle life unless treated successfully. In some cases, it may decrease in severity or remit completely with old age.

Episodes typically last less than 30 minutes and involve one or a combination of physical assault, verbal assault, or destruction of property. If there is provocation it is usually from a known person and is seemingly minor in nature. Many individuals frequently have minor aggressive episodes in the interim between severely aggressive/destructive episodes. Considerable distress, social, financial, occupational, or legal or impairments typically result from these episodes.

22.3.6 Treatments

22.3.6.1 Psychological Treatments

Few systematic data are available on response to treatment. Some of the recommended treatment approaches to IED are based on treatment studies of impulsivity and aggression in the setting of other mental disorders and general medical conditions. Thus, no standard regimen for the treatment of IED can currently be recommended. Both psychological and somatic therapies have been employed. A prerequisite for both modalities is the willingness of the individual to acknowledge some responsibility for the behavior and participate in attempts to control it.

The major psychotherapeutic task of treating this population involves teaching them how to recognize their own feeling states and especially the affective state of rage. Lack of awareness of their own mounting anger is presumed to lead to the buildup of intolerable rage that is then discharged suddenly and inappropriately in a temper outburst. Patients are therefore taught how to first recognize and then verbalize their anger appropriately. In addition, during the course of insight-oriented psychotherapy, they are encouraged to identify and express the fantasies surrounding their rage. Group psychotherapy for temper-prone patients has also been described. The cognitive–behavioral model of psychological treatment, or versions of CBT such as dialectic behavior therapy, may be usefully applied to problems with anger and rage management.

22.3.6.2 Somatic Treatments

Several classes of medications have been used to treat IED and impulsive aggression in the context of other disorders. These included beta-blockers (propranolol and metoprolol), anticonvulsants (carbamazepine and valproic acid), lithium, antidepressants (tricyclic antidepressants and serotonin-reuptake inhibitors), and antianxiety agents (lorazepam, alprazolam, and buspirone).

A substantial body of evidence supports the use of propranolol, often in high doses for impulsive aggression in patients with chronic psychotic disorders and mental retardation. Lithium has been shown to have antiaggressive properties and may be used to control temper outbursts. In patients with comorbid major depressive disorder, OCD, or Cluster B and C personality disorders (see Chapter 19), SSRIs may be useful. Overall, in the absence of more controlled clinical trials, the best approach may be to tailor the psychopharmacologic agent to coexisting psychiatric comorbidity. In the absence of comorbid disorders, carbamazepine, titrated to antiepileptic blood levels, may be used.

22.4.1 Diagnosis and Diagnostic Features

Kleptomania shares with all other ICDs the recurrent failure to resist impulses. Unfortunately, in the absence of epidemiologic studies, little is known about kleptomania. Clinical case series and case reports are limited. Family, neurobiologic, and genetic investigations are not available. There are no established treatments of choice. The reader of this secton must keep that in mind.

Kleptomania was designated a psychiatric disorder in 1980. It is currently classified in DSM-IV-TR as an ICD but is still poorly understood. The diagnostic criterion, which focuses on the senselessness of the items stolen, has often been considered the criterion that distinguishes kleptomania patients from ordinary shoplifters, but interpretation of this criterion is controversial. Patients with kleptomania may in fact desire the items they steal and be able to use them, but do not need them. This may be particularly the case with kleptomania patients who hoard items, for which multiple versions of the same item are usually not needed, but the item itself may be desired and may be of practical use to the patient. People with kleptomania often report amnesia surrounding the shoplifting act, and deny feelings of tension or arousal prior to shoplifting and feelings of pleasure or relief after the thefts. They often recall entering and leaving a store but have no memory of events in the store, including the theft. Others, who are not amnestic for the thefts, describe shoplifting as“automatic” or “a habit,” and may also deny feelings of tension prior to a theft or pleasure after the act, although they report an inability to control their shoplifting. Some report that they felt tension and pleasure when they started stealing, but it became a “habit” over time. Some speculate that patients who are amnestic for shoplifting or who do so “out of habit” represent two subtypes of kleptomania.

At presentation, the typical patient suffering from kleptomania is a 35-year-old woman who has been stealing for about 15 years and may not mention kleptomania as the presenting complaint or in the initial history. The patient may complain instead of anxiety, depression, lability, dysphoria, or manifestations of character pathology. There is often a history of a tumultuous childhood and poor parenting, and in addition acute stressors may be present, such as marital or sexual conflicts. The patient experiences the urge to steal as irresistible, and the thefts are commonly associated with a thrill, a “high,” a sense of relief, or gratification. Generally, the behavior has been hard to control and has often gone undetected by others. The kleptomania may be restricted to specific settings or types of object, and the patient may or may not be able to describe rationales for these preferences. Quite often, the objects taken are of inherently little financial value, or have meaningless financial value relative to the income of the person who has taken the object. Moreover, the object may never actually be used. These factors often help distinguish criminal theft from kleptomania. The theft is followed by feelings of guilt or shame and, sometimes, attempts at atonement.