Manic-depressive illness — I: clinical characteristics of bipolar disorder subtypes

Abstract The clinical and demographic features of 100 bipolar disorder patients, who were categorised into bipolar I, bipolar II, unipolar mania and rapid cycling groups, and who were further classified on the basis of the sequence of occurrence of the manic and depressive episodes within each cycle, are compared. Bipolar I (including unipolar manic) patients, 77% of whom had a sequence of moods where mania preceded depression (Mania-Depression – normothymic Interval: M.D.I.) constituted 69% of the total sample. Six per cent were classified as bipolar II and 25% has a rapid cycling disorder. Patients who had an M.D.I. sequence of moods, whether rapid or non-rapid cycling, had a younger age of onset, a higher male:female ratio and a stronger family history of bipolar disorder than patients whose depression preceded mania (D.M.I.). Unipolar manic patients, 12% of the sample, had a comparable age of onset, a greater family history of bipolarity and more frequent hospitalisations than the bipolar I-M.D.I. group. Rapid cycling patients had a lower mean serum thyroxine concentration than the non-rapid cycling bipolar disorder patients. This study supports the rationale for distinguishing bipolar patients with an M.D.I, sequence from those with a D.M.I, pattern and rapid cyclers from non-rapid cyclers.