Handbook of Disease Burdens and Quality of Life Measures pp 4157-4157 | Cite as
BD is not a single disorder, but a category of mood disorders defined by the presence of one or more episodes of abnormally elevated mood, clinically referred to as mania. Individuals who experience manic episodes also commonly experience depressive episodes or symptoms, or mixed episodes which present with features of both mania and depression. These episodes are normally separated by periods of normal mood, but in some patients, depression and mania may rapidly alternate, known as rapid cycling. The disorder has been subdivided into bipolar I, bipolar II and cyclothymia based on the type and severity of mood episodes experienced.