Intermittent explosive disorder

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Intermittent explosive disorder (abbreviated IED) is a behavioral disorder characterized by extreme expressions of anger, often to the point of uncontrollable rage, that are disproportionate to the situation at hand. It is currently categorized in the Diagnostic and Statistical Manual of Mental Disorders as an impulse control disorder. IED belongs to the larger family of Axis I impulse control disorders listed in the DSM-IV-TR, along with kleptomania, pyromania, pathological gambling, and others.^[1] Impulsive aggression is unpremeditated, and is defined by a disproportionate reaction to any provocation, real or perceived. Some individuals have reported affective changes prior to an outburst (e.g., tension, mood changes, energy changes, etc.).^[2]

A 2006 study suggests that the disorder is considerably more prevalent than previously thought. In a study of almost 10,000 individuals 18 years or older, lifetime episodes were reported at 7.3%, while 12-month occurrences were reported at 3.9%. This suggests a mean lifetime occurrence of 43 instances, with an average of $1359 in property damage.^[3]

A 2005 study conducted in the U.S. State of Rhode Island found the prevalence to be 6.3% (SE, +/- 0.7%) for lifetime DSM-IV IED in a study of 1300 patients under psychiatric evaluation.^[4] Prevalence is higher in men than in women.^[5] The disorder itself is not easily characterized and often exhibits comorbidity with other mood disorders, particularly bipolar disorder.^[6] Individuals diagnosed with IED report their outbursts were brief (lasting less than an hour), with a variety of bodily symptoms (sweating, chest tightness, palpitations) reported by a third of one sample. The violent acts were frequently reported accompanied by a sensation of relief, and in some cases, pleasure, but accompanied by remorse after the fact.^[6]

[edit] Diagnosis & treatment

The DSM-IV criteria for IED include: the occurrence of discrete episodes of failure to resist aggressive impulses that result in violent assault or destruction of property, the degree of aggressiveness expressed during an episode is grossly disproportionate to provocation or precipitating psychosocial stressor, and, as previously stated, diagnosis is made when other mental disorders that may cause violent outbursts (e.g., antisocial personality disorder, borderline personality disorder, attention deficit/hyperactivity disorder, etc.) have been ruled out.^[6] Furthermore, the acts of aggression must not be due to a general medical condition, e.g., a head injury, Alzheimer’s disease, etc., or due to substance abuse or medication.^[6] Diagnosis is made using a psychiatric interview to affective and behavioral symptoms to the criteria listed in the DSM-IV.

Treatment is achieved through both cognitive behavioral therapy and psychotropic medication regiments. Therapy aids in helping the patient recognize the impulses in hopes of achieving a level of awareness and control of the outbursts, along with treating the emotional stress that accompanies these episodes. Multiple drug regimens are frequently indicated for IED patients. Tricyclic antidepressants and selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine, fluvoxamine, and sertraline appear to alleviate some pathopsychological symptoms; the reasons for such will be explained further in the subsequent section.^[2][7] GABAergic mood stabilizers and anticonvulsive drugs such as gabapentin, lithium, carbamazepine, and divalproex seem to aid in controlling the incidence of outbursts.^[2][5][8] Anxiolytics help alleviate tension and may help reduce explosive outbursts by increasing the provocative stimulus tolerance threshold, and are especially indicated in patients with comorbid obsessive-compulsive or other anxiety disorders.^[5]

[edit] Pathophysiology

Impulsive behavior, and especially impulsive violence predisposition has been correlated to a low brain serotonin turnover rate, indicated by a low concentration of 5-Hydroxyindoleacetic acid (5-HIAA) in the cerebral spinal fluid (CSF). This substrate appears to act on the suprachiasmatic nucleus in the hypothalamus, which is the target for serotonergic output from the dorsal and median raphe nuclei playing a role in maintaining the circadian rhythm and regulation of blood sugar. A tendency towards low 5-HIAA may be hereditary. A putative hereditary component to low CSF 5-HIAA and concordantly possibly to impulsive violence has been proposed. Other traits that correlate with IED are low vagal tone and increased insulin secretion. A suggested explanation for IED is a polymorphism of the gene for tryptophan hydroxylase, which produces a serotonin precursor; this genotype is found more commonly in individuals with impulsive behavior.^[9]

IED may also be associated with lesions in the prefrontal cortex, with damage to these areas including the amygdala increasing the incidence of impulsive and aggressive behavior and the ability to predict the outcomes of an individual's own actions. Lesions in these areas are also associated with improper blood sugar control, leading to decreased brain function in these areas, which are associated with planning and decision making.^[10] A national sample in the United States estimated that 16 million Americans may fit the criteria for IED.^[3]

[edit] References

[edit] External links

• University of Minnesota Impulse Control Disorders Clinic