The rapid-cycling subtype of bipolar disorder is defined by how many episodes within one year?

1. Some patients with bipolar disorder experience a rapid-cycling subtype. 2. It is characterised by at least four manic episodes within one year, or by some combination of at least four manic and major depressive episodes in that time. 3. The count is therefore four episodes, and depressive episodes may be included in reaching it. 4. Two episodes with six stable months would not meet the count, and six manic episodes sets the bar higher than required. 5. A run of depressive episodes with no mania could not be bipolar disorder at all, since a manic episode is required for the diagnosis. _Source: OpenStax Psychology (1st ed., CC BY 4.0), Ch 15 "Psychological Disorders", section 15.7 Mood Disorders_