Manic episodes may in some cases be precipitated by antidepressant therapy and sleep deprivation. A minority of patients with bipolar disorder have more than three recurrences a year. These patients, defined as rapid cyclers, tend to be refractory to treatment and respond poorly to lithium. There is preliminary evidence that some rapid cyclers may respond preferentially to the anticonvulsive agent carbamazepine. Rapid cyclers and those with more classic bipolar disorder are frequently found in the same family, which suggests that the two forms of the illness do not have a separate genetic basis.
Rapid cycling occurs more commonly in women.
A high percentage of patients have onset of rapid cycling while being treated with antidepressants. There are preliminary data to suggest that the antidepressant bupropion may be the least problematic in this regard. Thyroid abnormalities may also predispose to rapid cycling. As is the case for major depression, there are no pathognomonic markers for bipolar disorder. Therefore, diagnosis must be made on the basis of clinical presentation, course of illness, and, when available, family history.