Manic-Depressive Cycles in Bipolar Disorder: Clinical and Treatment Implications

Cycle patterns of bipolar disorders (BDs) have been previously shown to be associated with clinical characteristics and response to lithium salts. Here, we evaluated the distribution of different types of manic-depressive cycles in a large sample of patients with BD. The associations between a mania-depression-interval (MDI) course and depression-mania-interval (DMI) course with sociodemographic/clinical factors were also assessed in order to define specific clinical profiles.

In this cross-sectional study, 806 patients with BD admitted to the Psychiatric Unit of San Luigi Gonzaga Hospital in Orbassano and Molinette Hospital in Turin, Italy, were recruited. Patients were grouped according to the following course patterns: MDI, DMI, continuous cycling (CC, <4 episodes/year without intervals), rapid cycling (RC, ≥4 episodes/year), and irregular (IRR) cycling. We compared several sociodemographic and clinical variables in an MDI versus DMI course by means of ANOVA and Pearson χ2 with Bonferroni correction.

Bipolar cycles were distributed as follows: 50.2% IRR course, 31.5% MDI course, 16% DMI course, 1.2% CC, and 1% RC. Compared to DMI course, patients with an MDI course were more often men, younger, with an earlier onset, a manic polarity onset, and more lifetime compulsory admissions. They were more frequently treated with lithium and antipsychotics. Patients with a DMI course had older age at diagnosis and at first mood-stabilizer treatment and were more often misdiagnosed with a major depressive disorder. These patients were more commonly treated with anticonvulsants, and they had more frequently failed treatment trials with lithium salts in the past.

This study supports the utility of classifying BD according to their course patterns. This classification holds prognostic as well as therapeutic implications.