Other meta-analyses have found lifetime prevalence of BP-II up to 1.57%. In the United States, the estimated lifetime prevalence of BP-II was found to be 1.1%, with a 12-month prevalence of 0.8%. The mean age of onset for BP-II was 20 years. Thus far, there have been no studies that have conclusively demonstrated that an unequal distribution of bipolar disorders across sex and ethnicity exists.It must be noted that a vast majority of studies and meta-analysis do not differentiate between BP-I and BP-II, and current epidemiology data may not accurately describe true prevalence and incidence. In addition, BP-II is underdiagnosed in practice, and it is easy to miss milder forms of the condition. History
In 19th century psychiatry, mania covered a broad range of intensity, and hypomania was equated by some to concepts of partial insanity or monomania. A more specific usage was advanced by the German neuro-psychiatrist Emanuel Ernst Mendel in 1881, who wrote "I recommend (taking under consideration the word used by Hippocrates) to name those types of mania that show a less severe phenomenological picture, hypomania". Narrower operational definitions of hypomania were developed from the 1960s/1970s. The first diagnostic distinction to be made between manic-depression involving mania and involving hypomania came from Carl Gustav Jung in 1903.
Benefits include prevention of relapse and improved maintenance medication adherence. These include psychotherapy (e.g. cognitive behavioral therapy, psychodynamic therapy, psychoanalysis, interpersonal therapy, behavioral therapy, cognitive therapy, and family-focused therapy), social rhythm therapy, art therapy, music therapy, psychoeducation, mindfulness, and light therapy. Meta-analyses in the literature has shown that psychotherapy plus pharmacotherapy was associated with a lower relapse rate compared with patients treated with pharmacotherapy alone. However, relapse can still occur, despite continued medication and therapy. People with bipolar disorder may develop dissociation to match each mood they experience. For some, this is done intentionally, as a means by which to escape trauma or pain from a depressive period, or simply to better organize ones life by setting boundaries for ones perceptions and behaviors. Prognosis
There is evidence to suggest that BP-II has a more chronic course of illness than BP-I. This constant and pervasive course of the illness leads to an increased risk in suicide and more hypomanic and major depressive episodes with shorter periods between episodes than BP-I patients experience. The natural course of BP-II, when left untreated, leads to patients spending the majority of their lives with some symptoms, primarily stemming from depression. Their recurrent depression results in personal distress and disability.This disability can present itself in the form of psychosocial impairment, which has been suggested to be worse in BP-II patients than in BP-I patients.