Course sequences in bipolar disorder: depressions preceding or following manias or hypomanias.

Background: Inferior response to lithium treatment has been reported in bipolar disorder (BD) patients with mania or hypomania following episodes of major depression (DMI) versus preceding depression (MDI), with intervening euthymic periods. However, additional characteristics of BD course-patterns require further assessment.

Methods: We reviewed computerized clinical records and life-charts of 855 DSM-IV-TR BD-I or -II patients assessed and followed at mood-disorder centers in Cagliari or Rome to characterize their predominant course-sequences.

Results: Morbidity over an average of 9.5 cycles in 18 years was characterized for sequencing of illness-episodes and euthymic intervals. Prevalent sequences included: major depression-hypomania (15.0%), mania-major depression (14.6%), major depression-mania (11.6%), and rapid-cycling (9.6%). Among subjects grouped by course-sequences (based on mania, mixed-states, or hypomania and major or minor depression), depression-before-[hypo]mania (DMI) cases were more likely to be women, diagnosed BD-II, have first-episodes of depressive or anxiety disorder, spend more time ill in depression, and benefit less with long-term mood-stabilizing treatments than with the opposite pattern (MDI). MDI patients were more likely to have substance-abuse and receive long-term mood-stabilizer treatments. Meta-analysis of 5 previous reports plus present findings found inferior treatment-response in DMI vs. MDI cases at a pooled risk-difference of 29% [CI: 18-40%] (p<0.0001).

Limitations: Some data were retrospective and subject to recall bias, and treatment was clinical (non-randomized).

Conclusions: The DMI course was strongly associated with first-episode depression or anxiety, excess depressive morbidity, and inferior treatment response, especially for depression.