Disruptive Mood Dysregulation Disorder 159
many other syndromes, differentiation of disr uptive mood dysregulation disorder from bi-
polar disorder and oppositional  defiant disorder requires pa rticularly careful assessment. 
Bipolar disorders. The central feature differentiating disruptive mood dysregulation disor-
der and bipolar disorders in children involves the longitudinal course of the core symptoms. In
children, as in adults, bipolar I disorder and bipo lar II disorder manifest as an episodic illness
with discrete episodes of mood perturbation that can be differentiated from the child’s typical
presentation. The mood perturbation that occurs  during a manic episode is distinctly different
from the child’s usual mood. In addition, during a manic episode, the change in mood must be
accompanied by the onset, or worsening, of associated cognitive, behavioral, and physical
symptoms (e.g., distractibility, increased goal-dir ected activity), which are also present to a de-
gree that is distinctly different from the child’s  usual baseline. Thus, in the case of a manic ep-
isode, parents (and, depending on  developmental level, children) should be able to identify a
distinct time period during which the child’s  mood and behavior were markedly different
from usual. In contrast, the irritability of disr uptive mood dysregulation disorder is persistent
and is present over many months; while it may wax and wane to a certain degree, severe irri-
tability is characteristic of the child with disr uptive mood dysregulation disorder. Thus, while
bipolar disorders are episodic conditions, disrup tive mood dysregulation disorder is not. In
fact, the diagnosis of di sruptive mood dysregulation disorder  cannot be assi gned to a child