In 1850, Jean-Pierre Falret described "circular insanity" (la folie circulaire, French pronunciation: ​[la fɔli siʁ.ky.lɛʁ]); the lecture was summarized in 1851 in the "Gazette des hôpitaux" ("Hospital Gazette"). Three years later, in 1854, Jules-Gabriel-François Baillarger (1809–1890) described to the French Imperial Académie Nationale de Médecine a biphasic mental illness causing recurrent oscillations between mania and melancholia, which he termed folie à double forme (French pronunciation: ​[fɔli a dubl fɔʀm], "madness in double form"). Baillargers original paper, "De la folie à double forme," appeared in the medical journal Annales médico-psychologiques (Medico-psychological annals) in 1854.These concepts were developed by the German psychiatrist Emil Kraepelin (1856–1926), who, using Kahlbaums concept of cyclothymia, categorized and studied the natural course of untreated bipolar patients. He coined the term manic depressive psychosis, after noting that periods of acute illness, manic or depressive, were generally punctuated by relatively symptom-free intervals where the patient was able to function normally.The term "manic–depressive reaction" appeared in the first version of the DSM in 1952, influenced by the legacy of Adolf Meyer. Subtyping into "unipolar" depressive disorders and bipolar disorders has its origin in Karl Kleists concept – since 1911 – of unipolar and bipolar affective disorders, which was used by Karl Leonhard in 1957 to differentiate between unipolar and bipolar disorder in depression. These subtypes have been regarded as separate conditions since publication of the DSM-III.
In general, bipolar disorder in children was not recognized in the first half of the twentieth century. This issue diminished with an increased following of the DSM criteria in the last part of the twentieth century. The diagnosis of childhood bipolar disorder, while formerly controversial, has gained greater acceptance among childhood and adolescent psychiatrists. American children and adolescents diagnosed with bipolar disorder in community hospitals increased 4-fold reaching rates of up to 40% in 10 years around the beginning of the 21st century, while in outpatient clinics it doubled reaching 6%. Studies using DSM criteria show that up to 1% of youth may have bipolar disorder. The DSM-5 has established a diagnosis—disruptive mood dysregulation disorder—that covers children with long-term, persistent irritability that had at times been misdiagnosed as having bipolar disorder, distinct from irritability in bipolar disorder that is restricted to discrete mood episodes. Elderly
Bipolar disorder is uncommon in older patients, with a measured lifetime prevalence of 1% in over 60s and a 12-month prevalence of 0.1–0.5% in people over 65. Despite this, it is overrepresented in psychiatric admissions, making up 4–8% of inpatient admission to aged care psychiatry units, and the incidence of mood disorders is increasing overall with the aging population. Depressive episodes more commonly present with sleep disturbance, fatigue, hopelessness about the future, slowed thinking, and poor concentration and memory; the last three symptoms are seen in what is known as pseudodementia.