But that's not quite the whole picture; depression is by far the most pervasive feature of the illness, while the manic phase usually involves a mix of irritability, anger, and depression, with or without euphoria. The elation may manifest as unusual energy and overconfidence, playing out in bouts of overspending or promiscuity.
The disorder most often starts in young adulthood, but also occurs in children and adolescents. Misdiagnosis is common; the condition is typically confused with everything from attention-deficit-hyperactivity disorder to schizophrenia to borderline personality disorder.
Biological factors probably create vulnerability to the disorder, and experiences such as sleep deprivation can kick off manic episodes.
While the depression of bipolar disorder can resist treatment, mood swings and recurrences can often be delayed or prevented with a mood stabilizer, on it's own or combined with other drugs. Psychotherapy is an important adjunct to pharmacotherapy, especially for dealing with the work and relationship problems that can accompany the disorder.