Referring to bipolar disorder in which four or more episodes of mood disturbance (manic, hypomanic, or major depressive episode) occur within 1 year.
Four or more episodes of depression, mania, hypomania, or other alternating mood disturbances occurring in a single year. Roughly 10% of patients with bipolar illness have this condition; more men than women are affected. Lithium carbonate is less effective in treating rapid cycling than in treating other forms of bipolar disorder.
Four or more instances of manic, hypomanic, mixed, or depressive episodes occurring within a span of 12 months.