quality:correction, structural:scholar_edition, linguistic:voice_change
Rapid cycling

Most people who meet criteria for bipolar disorder experience a number of episodes, on average 0.4 to 0.7 per year, lasting three to six months. Rapid cycling, however, is a course specifier that may be applied to any bipolar subtype. It is defined as having four or more mood disturbance episodes within a one-year span. Rapid cycling is usually temporary but is common amongst people with bipolar disorder and affects 25.8–45.3% of them at some point in their life. These episodes are separated from each other by a remission (partial or full) for at least two months or a switch in mood polarity (i.e., from a depressive episode to a manic episode or vice versa). The definition of rapid cycling most frequently cited in the literature (including the DSM-V and ICD-11) is that of Dunner and Fieve: at least four major depressive, manic, hypomanic or mixed episodes during a 12-month period. The literature examining the pharmacological treatment of rapid cycling is sparse and there is no clear consensus with respect to its optimal pharmacological management. People with the rapid cycling or ultradian subtypes of bipolar disorder tend to be more difficult to treat and less responsive to medications than other people with bipolar disorder.