Impulse-Control Disorders

Epidemiology and Risk Factors

Intermittent explosive disorder is more common than previously considered, with a lifetime prevalence of 7%. Men account for approximately 80% of the cases. Intermittent explosive disorder and personality change due to a general medical condition, aggressive type, are the diagnoses most often given to a patient with episodic violent behavior. Risk factors include physical abuse in childhood, a chaotic family environment, substance abuse, and psychiatric disorders in the patient or his or her relatives. The most common co-morbid disorders are mood disorders, anxiety disorders, and substance use disorders.

Pathophysiology

This disorder represents a complex convergence of psychosocial and neurobiological factors. Some studies implicate serotonin neurotransmission, as evidenced by lower cerebrospinal fluid (CSF) levels and by platelet serotonin receptor expression and re-uptake. An elevated testosterone level may play a role in episodic violence. An inverse relationship between aggression and CSF levels of oxytocin has also been reported. Imaging studies have suggested a dysfunctional cortico-limbic network, with exaggerated amygdala reactivity and diminished orbito-frontal cortex and anterior cingulated activation. Soft neurological signs may be present and reflect either trauma from earlier life experiences or genetic underpinnings of the violent behavior. Family members frequently have similar violent outbursts, as well as a host of psychiatric diagnoses, supporting both an environmental and a genetic etiology, with genes for the serotonin transporter and monoamine oxidase (MAO) type A (MAO _A ) interacting with childhood maltreatment and adversity to predispose to violence.

Clinical Features and Diagnosis

Intermittent explosive disorder commonly arises in childhood and adolescence, with the mean age of onset ranging from 13 to 21 years. An episode of violence may arise in the setting of increased anger and emotional arousal before the loss of control that is out of proportion to the precipitating stressor. Aggressive outbursts in this disorder are characterized by their rapid onset, with little to no warning and that typically last less than 30 minutes.

These patients may have a baseline of anger and irritability. Their lifestyle can be marginal; the disorder may make maintaining a job and stable relationships difficult. The presence of substance abuse further complicates both the diagnosis and the course. The most important feature of this disorder is that numerous other diagnoses must be ruled out before it can be diagnosed.

Most violent behavior can be accounted for by a variety of psychiatric and medical conditions, including seizures, head trauma, neurological abnormalities, dementia, delirium, and personality disorders (of the borderline or antisocial type). Anger attacks associated with major depression must also be ruled out. Further, psychosis from schizophrenia or a manic episode may cause episodic violence. Aggressive outbursts while intoxicated or while withdrawing from a substance of abuse would prevent making the diagnosis of intermittent explosive disorder ( Box 23-1 ). Intermittent explosive disorder carries significant morbidity, with 180 related injuries per 100 lifetime cases.

Treatment

Psychopharmacology (e.g., anticonvulsants, lithium, beta-blockers, anxiolytics, neuroleptics, antidepressants [both serotonergic agents and polycyclics], and psychostimulants) can effectively control the chronic manifestations of this disorder. Randomized control trials have shown benefit of fluoxetine as well as group and individual cognitive-behavior therapy (CBT). The evidence for antiepileptic drugs in treating aggression is less robust, with four antiepileptics (valproate/divalproex, carbamazepine, oxcarbazepine, and phenytoin) showing efficacy in at least one study, but with other studies of three of those drugs showing no significant benefit. The acute management of aggressive and violent behavior may also require use of physical restraints and rapid use of parenterally-administered neuroleptics and benzodiazepines (see Chapter 65 ).