Intermittent Explosive Disorder (IED) – Introduction

• Intermittent Explosive Disorder (IED) is an impulse control disorder characterized by recurrent, episodic, impulsive aggression; out of proportion to real or perceived stressors or threats. ¹

ICD-10CM CODES
F63.8	Other impulse disorders
F63.81	Intermittent explosive disorder
F63.9	Habit and impulse disorder, unspecified
DSM-5 CODE
312.34	Intermittent explosive disorder

EPIDEMIOLOGY & DEMOGRAPHICS

Prevalence

Using DSM-5 criteria, the lifetime prevalence of intermittent explosive disorder is estimated to be approximately 4% in the general population.

Predominant Sex & Age

More common in males and in individuals under the age of 50.

Peak Incidence

• Occurs earlier in life, with mean age at onset of about 14 years. ²

Risk Factors

Prior history of or exposure to violence, or trauma. There is evidence that substance use disorders place patients at risk of developing this condition. ³

Genetics

Patients with intermittent explosive disorder (IED) are more likely to have first-degree relatives with the disorder. In addition, adoption and twin studies suggest that >50% of the variance in aggression is related to genetic factors. ⁴

Neurobiology

• •Dysfunction in neuronal networks involved in impulse and emotional regulation, including amygdala-orbitofrontal cortical network.
• •Deficiency in the neurotransmitter serotonin has been implicated.
• •Inflammation may play a role. Numerous markers of oxidative stress are increased in patients with IED compared to controls.

CLINICAL PRESENTATION ¹

• •Several episodes of verbal or physical aggression; the latter may include attacks on other people, towards animals or towards objects.
• •The aggression is out of proportion to the perceived stressors or threats.
• •The aggression is impulsive, not premeditated and not done to further a goal.
• •The aggression causes distress or impairment in functioning.
• •The aggression is not better accounted for by another disease process.
• •Patients often do not recall the event, or recall is hazy.
• •Episodes generally occur twice weekly for at least 3 mo; alternatively, 3 discrete episodes occurring over 12 mo can qualify if they involve damage or destruction to property or physical assault resulting in injury.
• •The patient is at least 6 yr of age or equivalent developmental age.

COMORBIDITY

Comorbid psychiatric conditions are generally present with IED at levels higher than the general population and include depression, anxiety, substance use disorder, and cluster B personality disorders. ⁵

DIFFERENTIAL DIAGNOSIS

• •Psychiatrically, patients may suffer from mood, anxiety, psychotic, or personality disorders (primarily antisocial and borderline). In addition, patients may be under the effects of substances, or in withdrawal from them.
• •An example of a broad psychiatric differential would include the following: if under 18 then Disruptive Mood Dysregulation Disorder (DMDD) or Oppositional Defiant Disorder, in adults Conduct Disorder, ADHD, Borderline Personality Disorder, Autism Spectrum Disorder. ¹
• •Neuropsychologic conditions to consider include traumatic brain injury, dementia, delirium, temporal lobe epilepsy (TLE), multiple sclerosis (MS), and other brain lesions can cause similar behavior.

WORKUP

A thorough mental status and neurologic examination should be performed, with careful consideration for other neuropsychiatric conditions. Careful history taking assessing the time course, motive, and nature of behavioral outburst is imperative.

LABORATORY TESTS

• •Urine toxicology screen, as substance abuse is highly comorbid.
• •Dementia workup when appropriate: CBC, Chem 7, B-12, TSH, Folate, RPR.
• •Delirium workup when appropriate; associated signs and symptoms may be helpful for guidance, especially in clinical settings.

IMAGING STUDIES

• •Brain MRI (or at least a head CT), in cases where dementia, delirium, neurovascular disease, or brain lesions are suspected. The appropriate test should be ordered depending on the particulars of the case (such as MRI to evaluate for MS and subcortical disease).
• •EEG is indicated if seizure-related conditions (such as TLE) are suspected.

TREATMENT

• •Selective serotonin reuptake inhibitors (SSRIs) are considered first-line therapy.
• •If SSRI’s are ineffective, AEDs should be considered second line as efficacy has been demonstrated with phenytoin, oxcarbazepine, carbamazepine, lamotrigine, topiramate, and valproate.
• •Lithium has also been shown to be helpful.
• •There is evidence that ß-blockers (e.g., propranolol) can be helpful for IED, and anecdotally alpha-2 adrenergic agonists (e.g., clonidine) have also been used.
• •There is limited evidence to support use of antipsychotics in treating IED.

NONPHARMACOLOGIC THERAPY

• •Cognitive-behavioral therapy has been shown to be helpful for patients with IED.
• •Patients can be taught to examine their somatic sensations and change these through relaxation techniques.
• •Relapse prevention is focused on helping patients avoid explosive behaviors in the future.

COMPLEMENTARY & ALTERNATIVE MEDICINE

There is no evidence on the use of complementary or alternative medicine for this disorder.

RESPONSE

The goal of treatment is remission. Response can be quantified with a standardized rating scale including the Overt Aggression Scale-Modified (OAS-M). ⁶

PROGNOSIS

Not well studied; Impulse Control Disorders including IED are associated with a worse overall quality of life, interpersonal functioning, employment status, and mental health. ⁷

PEARLS & CONSIDERATIONS

PREVENTION

No prevention measures have been identified.

PATIENT & FAMILY EDUCATION

Psychoeducation to the patient and family may be helpful, especially in helping to identify triggers and supporting the use of coping skills.

References

1.American Psychiatric Association : Intermittent Explosive Disorder . Diagnostic and statistical manual of mental disorders- Text Revision ., ed 5 2002. American Psychiatric Association , Washington, DC

2.Scott K.M., et al.: The cross-national epidemiology of DSM-IV intermittent explosive disorder . Psychol Med 2016; 46 (15): pp. 3161-3172.

3.Coccaro E.F., et al.: Substance use disorders: relationship with intermittent explosive disorder and with aggression, anger, and impulsivity . J Psychiatr Res 2016; 81: pp. 127-132.

4.Coccaro E.F.: A family history study of intermittent explosive disorder . J Psychiatr Res 2010; 44 (15): pp. 1101-1105.

5.Coccaro E.F.: Psychiatric comorbidity in Intermittent Explosive Disorder . J Psychiatr Res 2019; 118: pp. 38-43.

6.Coccaro E.F.: The Overt Aggression Scale Modified (OAS-M) for clinical trials targeting impulsive aggression and intermittent explosive disorder: validity, reliability, and correlates . J Psychiatr Res 2020; 124: pp. 50-57.

7.Moffitt T.E., et al.: A gradient of childhood self-control predicts health, wealth, and public safety . Proc Natl Acad Sci U S A 2011; 108 (7): pp. 2693-2698.