The American Psychiatric Association's diagnostic and statistical manual of mental disorders describes manic episodes as follows: "The essential feature is a distinct period when the predominant mood is either elevated, expansive or irritable and when there are associated symptoms of the manic syndrome. These symptoms include hyperactivity, pressure of speech, flight of ideas, inflated self-esteem, decreased need for sleep, distractibility, and excessive involvement in activities that have a high potential for painful consequences, which are not recognized." In depressive episodes, by contrast, "The essential feature is either a dysphoric mood, usually depression, or loss of interest or pleasure in almost all usual activities and pastimes.This disturbance is prominent, relatively persistent, and associated with other symptoms of the depressive syndrome. These symptoms include appetite disturbance, change in weight, sleep disturbance, psychomotor agitation or retardation, decreased energy, feelings of worthlessness or guilt, difficulty concentrating or thinking, and thoughts of death or suicide or suicidal attempts."

Mild or moderate forms of manic-depression may imperceptibly shade into normalcy and, as such, are often not recognized by the layman. Paradoxically, when the illness is so severe that it reaches medical attention, it is often misdiagnosed as schizophrenia because of the dogma that catatonia, hallucinations, and delusions, particularly paranoid delusions, are diagnostic of schizophrenia. Consequently, many manic-depressives have been deprived of the striking benefits that antidepressants and lithium can offer.

A factor that has often interfered with the identification of manic] depressives is that culture and contemporary values strongly influence the way that people evaluate and judge behavior. Thus, behavior that is regarded as deviant in one era may not only be tolerated, but even extolled, in another. In contemporary western society hallucinations are held to reflect illness, but some primitive societies continue to value the ability to hallucinate. Social role imposes yet another influence on the perception of behavior. As in the case of Napoleon, manic behavior can propel an individual to a great military career, but the self-aggrandizement and disregard for others that occur in a manic can severely handicap a physician, a teacher, or an attorney. . .