Comparison of early- and late-onset rapid cycling affective disorders: clinical course and response to pharmacotherapy.

This study compared the clinical course and response to pharmacotherapy of patients with rapid cycling affective disorder (RCAD). A retrospective study was conducted on outpatients with affective disorder from 1991 to 1992 at Okayama University Medical School to select cases of RCAD. The subjects were 35 patients who fulfilled DSM-III-R criteria for mood disorder and had experienced at least four episodes of illness during the previous year. The subjects were divided into two groups according to their age at the first phase of affective illness: an early-onset group, consisting of patients aged 25 years or younger, and a late-onset group, consisting of patients aged 26 or older. There were 14 patients in the early-onset group and 21 in the late-onset group. Both the mean duration from onset to rapid cycling and the mean duration of each phase were shorter in the early-onset group than in the late-onset group. There were no significant differences between the groups in period of remission, character of the first episode, heredity, or thyroid function. Lithium carbonate therapy was more effective for reducing manic symptoms in the late-onset group than in the early-onset group, without maintaining a prophylactic effect in either group, whereas carbamazepine was more effective in the early-onset group. Antidepressants used in the depressive phase had a tendency to be more effective in the late-onset than in the early-onset group. However, rapid cycling induced by antidepressants was more evident in the late-onset than in the early-onset group. These findings supported the differentiation of RCAD into two groups based on age at onset, the early-onset group showing a rapid cycling course at an early stage and a good response to carbamazepine, the late-onset group having a relatively long disease duration until the appearance of a rapid cycling course and a good response to lithium carbonate in the manic phase and to antidepressants in the depressive phase.