Clinical relevance and treatment possibilities of rapid cycling in patients with bipolar disorder

In the actual version of the WHO diagnostic guidelines, the ICD-10, subtypes of bipolar disorder are not specified, in contrast to the American DSM-IV, where bipolar disorder has already been differentiated in bipolar I (severe manic and depressive episodes) and bipolar II disorder (depressive and hypomanic episodes). Furthermore, aspects of the longitudinal course of the illness, like rapid cycling (RC), are reflected as well. Rapid cycling is defined as four or more affective episodes within one year of the illness. It has been postulated that rapid cycling is related with a poor response to lithium, to the same extent as mixed episodes or an atypical onset (depressive episode first) of the disease. Here, the current status of alternative pharmacological and supportive therapy of rapid cycling is presented and discussed. Furthermore, the article also displays biological parameters associated with rapid cycling like higher prevalence in women, hypothyreoidism, subtype of bipolar disorder, COMT-allele, influence of sleep or risk of antidepressant induced cycling.