Intermittent explosive disorder (IED) is part of the category of habit and impulse disorders, all of which have the common characteristic of inability or failure to resist a drive or impulse to do something which is harmful to self or others.
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The individual typically complains of inner tension which builds up until the act is committed, and experiences relief or pleasure once it is done. First called “monomanies instinctives” by Jean Etienne Esquirol, it is considered a disease of apparently purposeless irresistible urges.
These disorders have been described first in the third edition of the Diagnostic and Statistical Manual (DSM-III). The psychiatric component is shown by the following characteristics:
- The violence of the act is out of all proportion to the factor that was the immediate precipitating cause
- The individual always puts the blame for the loss of control on some other person or situation rather than accepting responsibility for the aggressive impulse and action
- Lack of desire and motivation to change this behavior
Both environmental and genetic factors have been studied for their contribution to IED.
- A family environment, which is characterized by verbal and physical violence and behavior, is strongly correlated with IED in the children. This may be because of the impact of childhood learning experiences, or due to shared genetic predispositions, as in other mental illnesses.
- A history of physical abuse or multiple traumatic experiences in childhood is also a risk factor for IED but is not universally found.
- Genetic factors may also operate in the transmission of the disorder. This may be due to differences in the way brain chemicals operate in these individuals.
- Any use of alcohol and/or drug use was much more common in IED patients, and multiple substance use increased the risk. Multiple substance abuse was even more strongly correlated with severity of IED, as was high-risk behavior in many forms.
- Peak incidence is in the teens, between the age of 6 and 40 years.
- Earlier age of onset was seen in males, at the age of 13 years, as compared to 19 years in females.
- IED had the earliest age of onset among all other disorders present in the same patient except for phobic anxiety, and thus it was unlikely to be caused by any of them.
- Other comorbid disorders include mood disorders, anxiety disorders, eating disorders, substance abuse, personality disorders and other impulse control disorders.
- Traumatic brain injury especially to the frontal cortex had occurred in some individuals who later became impulsive or had one of the impulse control disorders. This is important in that damage to the prefrontal cortex is known to produce such behavioral patterns.
- The presence of borderline, narcissistic, histrionic, and antisocial personality traits predict the risk of impulse control disorders, as does attention-deficit hyperactivity disorder (ADHD).
The characteristically manic symptoms in IED, the high rate of comorbidity with bipolar disorder, and the good response to mood-stabilizing drugs, may point to IED being a variant of bipolar disorder.