At least one-third of the time, the symptoms of bipolar disorder first appear in childhood or adolescence.
However, in children, it can be difficult to distinguish bipolar symptoms from those of other disorders, notes the May 2007 issue of the Harvard Mental Health Letter.
Children, especially young children, usually do not show the adult cycle of distinct mood episodes of mania and depression. Also, many symptoms that may stem from bipolar disorder also occur in other childhood disorders: moods fluctuating in very rapid cycles, sometimes from hour to hour; irritability and agitation; or bursts of rage. Bipolar disorder in children is especially difficult to distinguish from ADHD, since they share a number of symptoms—impulsiveness, distractibility, and hyperactivity. Up to 30% of children originally diagnosed with ADHD eventually receive a diagnosis of bipolar disorder.
Research suggests that some children diagnosed with bipolar disorder have a different condition, recently labeled “severe mood dysregulation.” Although both conditions involve periodic irritability and hyperactivity, electrical signals in the brains of children thought to have severe mood dysregulation are different from brain signals in children with bipolar disorder.