All children are irritable at one time or another. Irritability that exceeds what is expected for a child's developmental age may be an indication of an underlying mental health disorder. Irritability, defined as “a mood of easy annoyance and touchiness characterized by anger and temper outbursts,” is a clinical feature common to several childhood mental health disorders.1 When a mental disorder presents with irritability as one of its primary, debilitating symptoms, determining the correct diagnosis can be a clinical challenge. Accurate diagnosis informs important prognostic and treatment implications.
A DIAGNOSTIC CONTROVERSY
For more than a decade, some researchers have suggested that chronic, nonepisodic irritability is a manifestation of mania in children and indicates a diagnosis of pediatric bipolar disorder.2 This generalization is believed to be, in part, responsible for the nearly 500% increase in the diagnosis of pediatric bipolar disorder in the United States over the same time.3 Along with this increase came controversy as to whether children with chronic irritability truly had pediatric bipolar disorder. The Diagnostic and Statistical Manual of Mental Disorders (DSM V) describes pediatric bipolar disorder as having distinct periods of mood instability with well-preserved interepisode functioning.4
Those who believe bipolar disorder is a spectrum disorder with variable presentations argue that children do not always display true mania as seen in adults. Instead, children may express their mood dysregulation as poor tolerance for frustration and persistent emotional instability with severe outbursts.5
In 2009, in response to this diagnostic controversy, Leibenluft and colleagues proposed a new diagnostic category for children who manifested chronic, nonepisodic irritability.6 The researchers set out to determine if these children were a distinctly separate group from those who demonstrated the episodic manic symptoms typical of bipolar disorder. They termed the new disorder severe mood dysregulation and included children in this diagnostic category who demonstrated emotional dysregulation, expressed as severe irritability coupled with hyperarousal symptoms including insomnia, agitation, distractibility, racing thoughts, flight of ideas, and/or pressured speech.6
This classification has triggered further research to compare and contrast cohorts of children with episodic symptoms to those with chronic irritability. Research conducted by Stringaris and colleagues has found differences in family history and prognosis between children who present with classic, episodic symptoms of bipolar disorder and those who meet criteria for severe mood dysregulation.3
Children with nonepisodic irritability meeting the criteria for severe mood dysregulation are significantly less likely to have a parent diagnosed with bipolar disorder compared with children who exhibit the abnormal, episodic irritability classic of pediatric bipolar disorder.3 In a 7-year follow-up study by Brotman and colleagues, children meeting the criteria for severe mood dysregulation were found to have an increased risk of unipolar depression and/or generalized anxiety disorder, but not bipolar disorder, later in life.7
These findings, in addition to concerns about a substantial increase in bipolar disorder diagnoses in children, led the DSM V committee to establish a new diagnosis, disruptive mood dysregulation disorder (DMDD) for children with chronic, severe irritability and frequent temper outbursts.4
The DSM V categorizes DMDD, which may be diagnosed in children between the ages of 6 and 18 years, as a depressive disorder because children are at increased risk of developing depressive and anxiety disorders later in life.4
Central to a diagnosis of DMDD is the presence of chronic, unremitting irritability that is:
- present before age 10 years
- occurs in two or more settings (severe impairment in one setting and mild to moderate impairment in a second setting)
- has been exhibited for at least 1 year.4
This irritability manifests as frequent, severe temper outbursts that typically occur three or more times per week, usually secondary to frustration, and may result in aggression toward others. These outbursts are significantly out of proportion to what would be expected given the situation in which they occur and are not typical in relation to the child's developmental age.4
In addition to temper outbursts, the child is irritable or angry most of the day, for most days of the week and, although the severity of symptoms of DMDD may fluctuate over time, has persistent mood symptoms at baseline.4 These diagnostic criteria clearly differentiate chronic, severe irritability from episodic symptoms, with the latter reserved for a diagnosis of bipolar disorder.
PREVALENCE AND PROGNOSIS
Given the novelty of the diagnosis, the prevalence of DMDD remains unclear; however taking into consideration the prevalence of chronic and severe persistent irritability, the 1-year prevalence of DMDD is likely between 2% and 5% of the general pediatric and adolescent population.4 Prevalence is expected to be most common among school-age children and males.4
The subsequent development of bipolar disorder in children who meet criteria for DMDD is relatively rare, and symptoms of DMDD often improve as a child ages.4
Obtaining a thorough social history is important, particularly when a child has mood disturbances and a diagnosis of mental illness is being considered. The child's past and present life experiences may lead to other possible diagnoses such as post-traumatic stress disorder or abuse (Figure 1). School performance can help to provide an objective measure of how the child's symptoms are affecting his or her ability to function. DMDD rarely exists as a mental health disorder in and of itself, typically coexisting with attention deficit hyperactivity disorder and/or anxiety disorders, complicating the course of illness.4
The central differentiating factor in distinguishing bipolar disorder from DMDD is the periodicity of symptoms. Both disorders can manifest with irritable symptoms that create difficulty in functioning. However, the irritability seen in bipolar disorder is episodic and the patient's mood between episodes is clearly distinguishable from the irritable mood because the patient returns to his or her baseline nonirritable mood between episodes.4 In addition, DMDD should not be diagnosed in children younger than age 6 years or older than age 18 years; bipolar disorder does not have age parameters.4
Oppositional defiant disorder
Most children who meet diagnostic criteria for DMDD also meet diagnostic criteria for oppositional defiant disorder; however, in addition to emotional outbursts, children with DMDD also will have mood symptoms (which are not characteristic of children with oppositional defiant disorder) and are more significantly impaired.
Intermittent explosive disorder
According to the DSM V, the diagnostic criteria for intermittent explosive disorder require emotional outbursts to persist for 3 months or more, compared with 12 months in patients with DMDD. In addition, children who best meet criteria for intermittent explosive disorder do not have mood symptoms between outbursts.
DSM V criteria do not allow DMDD to be concurrently diagnosed with bipolar disorder, oppositional defiant disorder, or intermittent explosive disorder.
POTENTIAL COMORBID CONDITIONS
DMDD may coexist with attention deficit hyperactivity disorder (ADHD), major depressive disorder, persistent depressive disorder, anxiety disorder, and autism spectrum disorder.4 Note that the comorbid mental diagnosis alone does not explain the significance of the impairment in emotional self-regulation and irritability seen in children with DMDD.8
Differentiating pediatric bipolar disorder from DMDD is not only important for prognostic factors, but for treatment considerations. The decision to treat children with psychotropic medication should not be made without thoughtful consideration of the severity of symptoms and discussing nonpharmacologic interventions before starting medication.
Based on the success of parental training in addressing oppositional defiant disorder in younger children, implementing this training to address DMDD in these children is recommended. Although parental training has not shown efficacy in adolescents with oppositional defiant disorder, individualized cognitive behavioral therapy has been effective and is suggested for adolescents with DMDD.9
Having a good understanding of the child's life experiences can help healthcare providers formulate an individualized plan of care. Discussing the effect of the child's behavior on the family can help providers develop a comprehensive, holistic treatment plan. Parents and siblings may need emotional support because the aggression exhibited by a child with DMDD may be inflicted on family members.9
Clear pharmacologic treatment guidelines have yet to be established for DMDD.2,8 Research conducted by Dickstein and colleagues on severe mood dysregulation disorder seems to indicate that lithium is not effective in controlling severe, chronic irritability.10 More research is needed to determine the most effective ways to treat children with DMDD.
Given that children with DMDD often have other comorbid mental disorders, a recommended treatment approach is to follow established treatment guidelines for treating the comorbid disorders.2,8 For example, if a child has DMDD and ADHD, consider a stimulant medication; research conducted by the National Institute for Health and Care Excellence (NIHCE) has shown methylphenidate to be effective in reducing oppositionality in some children with ADHD.8,11 A child with DMDD and major depressive disorder or an anxiety disorder may be treated with cognitive behavioral therapy and/or a selective serotonin reuptake inhibitor.2,8
This treatment approach varies from the treatment of pediatric bipolar disorder, which may be treated with mood stabilizers, anticonvulsants, or antipsychotic medication.12 Studies of successful treatment of severe mood dysregulation included children with hyperarousal symptoms, a clear distinction between severe mood dysregulation and DMDD (which does not include hyperarousal symptoms in its diagnostic criteria).4,13,14 This is an important distinction given that an open-label drug trial involving children with severe mood dysregulation found that low doses of risperidone were effective in reducing irritability.13,14 Deducing that what was effective in treating severe mood dysregulation will be effective in treating DMDD should be done with caution, given the difference in symptomology. No study has examined the effect of antipsychotic medications on patients with DMDD, and the potential adverse reactions to these drugs, even with short-term use, limits their efficacy.9
The rate of bipolar disorder diagnoses in children has risen dramatically over the past decade, raising concerns that this does not represent a true increase in the prevalence of the disorder.14 Along with this increase has come an increase in the use of antipsychotic medications, which can have significant metabolic adverse reactions. Concern has grown over the potential for overuse of these medications in children.2,14 Clearly distinguishing and understanding the differences in chronic, nonepisodic severe irritability from the episodic symptoms of bipolar disorder may diminish this diagnostic trend and decrease the use of antipsychotic medication; however, this has yet to be seen.
Accurately diagnosing mental illness in children can be challenging and developing effective treatment plans is essential to maximizing functional outcomes. Children and their caregivers need support because these issues are complex and can affect multiple facets of their lives. Clinicians must know about community support resources and sources of referral to provide optimal care for these patients. More research also is needed on DMDD to establish clear treatment guidelines, as these children need the help of mental health professionals to improve their quality of life and maximize their potential.
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