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= Disruptive Mood Dysregulation Disorder (DMDD) =

Disruptive Mood Dysregulation Disorder (DMDD) is a psychiatric disorder, typically seen in children, characterized by persistently irritable or angry mood overlain with recurrent, severe temper outbursts. DMDD is classified as a mood disorder in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) and it may be a form of depression seen in young children. Longitudinal studies suggest that children with DMDD are at-risk for depression in later childhood or adolescence. The symptoms of DMDD resemble those of other childhood disorders, notably Attention-Deficit/Hyperactivity Disorder (ADHD), Oppopsital Defiant Disorder (ODD), and pediatric Bipolar Disorder. However, empirical studies have shown that DMDD is district from these other conditions. DMDD is a new disorder, first appearing in DSM-5 (2013). Because DMDD is relatively new, little is known about its course or etiology. Evidence-based treatments tend to involve medication to manage mood symptoms, behavior therapy to manage temper outbursts, and/or family therapy to address symptoms of depression.

Signs and Symptoms
Children with DMDD show severe and recurrent temper outbursts. Although many children have occasional tantrums, youths with DMDD have outbursts that are out of proportion in terms of their intensity or duration. These outbursts can be verbal or behavioral. Verbal outbursts often are described by observers as "rages" or "fits." Children may scream, yell, and cry for excessively long periods of time, sometimes with little provocation. Physical outbursts may be directed toward people of property. Children may throw objects; hit, slap, or bite others; destroy toys or furniture; or otherwise act in a harmful or destructive manner. To be diagnosed with DMDD, these outbursts must occur, on average, three or more times per week.

Children with DMDD also display persistently irritable or angry mood that is observable by others. Parents, teachers, and classmates describe these children as habitually angry, touchy, grouchy, or esily "set off." Irritability is a feature of many childhood disorders. For example, children with behavior problems (e.g., Oppositional Defiant Disorder), anxiety disorders (e.g., Generalized Anxiety Disorder), and other mood disorders (e.g., Major Depressive Disorder) can show irritability. However, the irritability or anger shown by children with DMDD is "persistent," that is, it is shown most of the day, nearly every day. Youths with DMDD, therefore, do not show episodic irritability or anger; they have mood problems that have typically lasted for months or years.

DSM-5 includes several additional diagnostic criteria which describe the duration, setting, and onset of the disorder:
 * The mood problems and outbursts must be present for at least 12 months. This criterion highlights the chronicity of the disorder and differentiates DMDD from mood disorders that are characterized by discrete episodes or cycles of irritability/excitement, such as Major Depressive Disorder or Bipolar Disorder.
 * The mood problems and outbursts must occur in at least two settings (e.g., home, school, with peers) and must be severe in at least one setting. This criterion highlights the severity of the disorder and differentiates DMDD from disruptive behavior that might occur only in one setting (e.g., a child tantrums only at home to avoid chores; a child is irritable only at school because of learning problems).
 * The disorder is first diagnosed only between the ages of 6 and 18 years. Furthermore, symptom onset must occur prior to age 10 years. These criteria highlight the fact that DMDD is a childhood disorder that should not be diagnosed in toddlers or preschoolers. Very young children often show temper outbursts (e.g., tantrums to obtain candy or a toy) which are not signs of DMDD. Furthemore, mood problems that first emerge in adolescence likely reflect other problems besides DMDD, such as another mood disorders or difficulty adjusting to psychosocial stressors.

Relationship to Other Childhood Disorders
The core features of DMDD, temper outbursts and chronic irritability, are sometimes seen in children and adolescents with several other psychiatric conditions. Differentiating DMDD from these other conditions can be difficult. Three disorders that most closely resemble DMDD are Attention-Deficit/Hyperactivity Disorder (ADHD), Oppositional Defiant Disorder (ODD), and pediatric Bipolar Disorder.

ADHD
ADHD is a neurodevelopmental disorder characterized by problems with inattention and/or hyperactivity-impulsivity. Children with DMDD often show several features of hyperactivity and impulsiveness characteristic of ADHD. However, DMDD can be differentiated from ADHD in at least two ways. First, DMDD is a mood disorder, whereas ADHD is a disruptive behavior disorder. A salient feature of DMDD is persistently irritable or angry mood. In contrast, children with ADHD do not typically display irritability or anger. Second, DMDD is characterized by severe, recurrent temper outbursts that are not characteristic of ADHD. Although many children with ADHD act impulsively, they typically do not show verbal or physical aggression toward other people or property. Children with ADHD can be diagnosed with DMDD, despite the fact they are two separate conditions.

Oppositional Defiant Disorder (ODD)
ODD is a disruptive behavior disorder characterized by oppositional, defiant, and sometimes hostile actions directed at other people. Like DMDD, ODD emerges in chidlhood and is often characterized by both irritable mood and angry outbursts. Furthermore, the features of ODD and DMDD are both persistent; children with these disorders usually experience signs and symptoms for months or years. Features of ODD and DMDD also frequently co-occur. Nearly all children with DMDD also meet diagnostic criteria for ODD. However, only about 15% of children with ODD meet diagnostic criteria for DMDD. Some experts believe DMDD is a severe form of ODD in which children's mood problems are the most salient symptom. In DSM-5, children cannot be diagnosed with both disorders. If a child meets criteria for both ODD and DMDD, only DMDD (the more serious disorder) is diagnosed.

Despite their similarity, DMDD can be differentiated from ODD in several ways. First, like ADHD, ODD is a disruptive behavior disorder not a mood disorder. Although children with ODD can show irritability and angry outbursts, their most salient feature is noncompliant and defiant behavior, such as ignoring parents, refusing to do chores, or acting in a spiteful or resentful manner. Second, children with ODD direct their oppositionality and defiance toward specific people. For example, a child with ODD may act defiantly toward his mother, but be compliant with his father. In contrast, children with DMDD direct their anger and physical aggression toward most people and also objects. For example, a child with DMDD may be tantrum with both parents, show irritability with teachers and classmates, and break objects when upset. Third, DMDD and ODD differ in the duration and severity of children's outbursts. Whereas a child with ODD may ignore parents' requests or stubbornly refuse to comply with their commands, a child with DMDD might yell, scream ,or hit his parents to express anger. The outbursts of children with DMDD often appear with little provocation and last much longer than expected. Finally, children with DMDD show different developmental outcomes than youths with ODD. Whereas youths with ODD are often at risk for developing more serious conduct problems, youths with DMDD are at greater risk for anxiety and depression in later childhood and adolescence.

Pediatric Bipolar Disorder
Bipolar Disorder is a mood disorder characterized by discrete manic or hypomanic episodes. Manic and hypomanic episodes are characterized by feelings of elevated, expansive, or irritable mood and increased activity or energy. Many children with Bipolar Disorder also show periods of irritability, moodiness, and increased levels of activity. Beginning in the 1990s, some clinicians began observing children with hyperactivity, irritability, and severe temper outbursts. These symptoms greatly interfered with their lives at home, school, and with friends. Because other diagnoses, like ADHD and ODD, did not capture the severity of children's irritability and anger, many of these children were diagnosed with Bipolar Disorder. Some experts asserted that children manifested Bipolar Disorder differently than adults. Whereas adults with Bipolar Disorder typically display discrete episodes of mania and discrete episodes of depression lasting weeks or months, children with Bipolar Disorder (they argued) may not show discrete manic and depressive episodes. Instead, they argued that children with Bipolar Disorder show persistent mood problems and irritability with frequent mood outbursts or "rages." Children's persistent irritability or anger, recurrent temper outbursts, and "ultra-rapid" cycling of mood were believed to be unique features of Bipolar Disorder in children.

Recent research, however, as shown that children with persistent irritability and angry outbursts often do not have Bipolar Disorder. Several longitudinal studies conducted at the National Institutes of Mental Health showed that children with chronic irritability and temper outbursts often developed later problems with anxiety and depression and rarely developed Bipolar Disorder in adolescence or adulthood. Consequently, the developers of DSM-5 created a new diagnsotic label, DMDD, to describe children with persistent irritability and angry outbursts. Because DMDD is closely associated with depresssion, it is classified as a unipolar mood disorder, not a bipolar disorder. Clinicians are urged to diagnose children with DMDD if they show persistent irritability and temper outbursts and to reserve the diagnosis of Bipolar Disorder for those youths who show classic symptoms of mania or hypomania.

Epidemiology and Course
Because DMDD is a new disorder, we do not yet have a good estimate of its prevalence. Epidemiological studies show that approximately 3.2% of children in the community have chronic problems with irritability and temper, the essential features of DMDD. These problems are probably more common among clinic-referred youths. Approximately 30% of children hospitalized for psychiatric problems meet diagnostic criteria for DMDD based on parental report and 15% meet criteria based on the observations of hospital staff. Several disorders co-occur with DMDD including ADHD, Generalized Anxiety Disorder, and Major Depressive Disorder.

Little is known about the course of DMDD. Most parents of children with DMDD report that their children first showed signs and symptoms of the disorder during the preschool years. The chornic irritability and angry outbursts that characterize DMDD often last through early adolescence if left untreated, although well-designed prospective longitudinal studies are lacking.

Etiology
The causes of DMDD are poorly understood. Several recent studies indicate that many youths with DMDD have difficulty attending, processing, and responding to negative emotional stimuli and social experiences in their everyday lives. For example, some studies have shown youths with DMDD to have problems interpreting the social cues and emotional expressions of others. These youths may be especially bad at judging others' negative emotional displays, such as feelings of sadness, fearfulness, and anger. Functional MRI studies suggest that under-activity of the amygdala, the brain area that plays a role in the interpretation and expression of emotions, is associated with these deficits. Deficits in interpreting social cues may predispose children to instances of anger and aggression in social settings with little provocation. For examples, youths with DMDD may selectively attend to negative social cues (e.g., others scowling, teasing) and minimize all other information about the social events. They may also misinterpret the emotional displays of others, believing others' benign actions to be hostile or threatening. Consequently, they may be more likely than their peers to act in impulsive and angry ways.

Children with DMDD may also have difficulty regulating negative emotions once they are elicited. To study these problems with emotion regulation, researchers asked children with DMDD to play computer games that are rigged so that children will lose. While playing these games, children with DMDD report more agitation and negative emotional arousal than their typically-developing peers. Furthermore, youths with DMDD showed markedly greater activity in the medial frontal gyrus and anterior cingulate cortex, than comparison youths. These brain regions are important because they are involved in evaluating and processing negative emotions, monitoring one's own emotional state, and selecting an effective response when upset, angry, or frustrated. Altogether, these findings suggest that youths with DMDD are more strongly influenced by negative events than other youths. They may become more upset and select less effective and socially acceptable ways to deal with negative emotions when they arise.

Medication
There is first-line medication used to treat DMDD. Because the mood stabilizing medication, lithium, is effective in treating adults with Bipolar Disorder, some physicians have used it to treat DMDD. However, randomized controlled trials have not shown lithium to be better than placebo in alleviating the signs and symptoms of DMDD. Currently, most physicians treat DMDD with a combination of medications that target the child's symptom presentation. For youths with DMDD alone, antidepressant medication is sometimes used to treat underlying problems with irritability and/or sadness. For youths with unusually strong temper outbursts, an atypical antipsychotic medication, such as risperidone, may be warranted. Both medications, however, are associated with signifciant side effects in children. Finally, for children with both DMDD and ADHD, stimulant medication is sometimes used to reduce symptoms of impulsivity.

Psychosocial Treatment
Several cognitive-behavioral interventions have been developed to help youths with chronic irritability and temper outbursts. Because many youths with DMDD show problems with ADHD and oppositional-defiant behavior, experts initially tried to treat these children using contingency management. This type of intervention involves teaching parents to reinforce children's appropriate behavior and punish (usually thorugh systematic ignoring or time out) inappropriate behavior. Although contingency management can be helpful for ADHD and ODD symptoms, it does not seem to reduce the most salient features of DMDD, namely, irritability and anger.

Recently, treatment for DMDD has involved cognitive and behavioral interventions that address the behavioral and emotional components of DMDD. This form of treatment is designed to improve children's emotion-regulation and social problem-solving skills. For example, Waxmonsky and colleagues have developed a treatment package for youths with DMDD and their parents. Treatment involves educating families about DMDD, teaching parents to manage children's behavior and angry outbursts, and helping children regulate their emotions and respond appropriately when angry or frustrated. Child and parent sessions run concurrently. When groups of children with DMDD practice anger management or social skills in one room, groups of parents learn similar child management techniques in an adjacent room. Concurrent sessions ensure that parents learn the same skills as children, so parents can practice and reinforce skills at home. For example, children learn how to differentiate various emotions, how to identify "triggers" that often elicit angry outbursts, and how to build a "toolkit" to cope with with social situations that often lead to problems. Similarly, parents learn how to identify and avoid "triggers" for their children's angry outbursts, how to deescalate tantrums when they occur at home, and how to manage their own negative emotions when interacting with their children. An initial evaluation of the treatment package showed that it was helpful in reducing children's disruptive behavior, alleviating symptoms of dysphoria, and improving the quality of parent-child interactions.

Genetic influences
Research indicates that parents pass on a tendency for externalizing disorders to their children that may be displayed in multiple ways, such as inattention, hyperactivity, or oppositional and conduct problems. This heritability can vary by age, age of onset, and other factors. Adoption and twin studies indicate that 50% or more of the variance causing antisociajjjvkjc,j,cl behavior is attributable to heredity for both males and females. ODD also tends to occur in families with a history of ADHD, substance use disorders, or mood disorders, suggesting that a vulnerability to develop ODD may be inherited. A difficult temperament, impulsivity, and a tendency to seek rewards can also increase the risk of developing ODD. New studies into gene variants have also identified possible gene-environment (G x E) interactions, specifically in the development of conduct problems. A variant of the gene that encodes the neurotransmitter metabolizing enzyme monoamine oxidase-A (MAOA), which relates to neural systems involved in aggression, plays a key role in regulating behavior following threatening events. Brain imaging studies show patterns of arousal in areas of the brain that are associated with aggression in response to emotion-provoking stimuli.