Research paperCircadian rhythm sleep-wake disorders as predictors for bipolar disorder in patients with remitted mood disorders

- Circadian rhythm dysfunction could be a predictor for bipolar disorder (BD) in mood disorders.
- One hundred four BD and 73 major depressive disorder (MDD) patients participated in this study.
- We compared prevalence of Circadian rhythm sleep-wake disorders (CRSWD) between BD and MDD subjects.
- The rate of CRSWD in BD subjects was significantly higher than that in MDD subjects.
- Comorbid CRSWD associated with BD in patients with remitted mood disorders.

BackgroundCircadian rhythm dysfunction is thought to play a key role in the pathogenesis of bipolar disorder (BD). We focused on circadian rhythm sleep-wake disorders (CRSWD) as possible predictors for bipolar disorder in patients with remitted mood disorders.MethodOne hundred four BD (41 type I and 63 type II) outpatients and 73 age- and sex-matched major depressive disorder (MDD) outpatients participated in this study. The subjects were asked to answer questionnaires including demographic variables, clinical course of the disorder, and family history of psychiatric disorders. Severity of mood status was evaluated by the Montgomery-Åsberg Depression Rating Scale and Young Mania Rating Scale. CRSWD was diagnosed by clinical interview and sleep logs based on the International Classification of Sleep Disorders, third edition.ResultsThe rate of CRSWD in BD subjects was significantly higher than that in MDD subjects (33.7% vs 9.6%; P < 0.001). A multiple logistic regression analysis revealed that comorbid CRSWD (OR = 3.35, 95% CI = 1.24 - 9.07; P = 0.018), two or more previous mood episodes within the past year (OR = 3.57, 95% CI = 1.10 - 11.63; P = 0.035), and antidepressant-related switch to mania/hypomania (OR = 10.01, 95% CI = 1.20 - 83.52; P = 0.033) were significantly associated with BD in patients with remitted mood disorders.ConclusionCRSWD, as well as other factors, could be diagnostic predictors for BD in patients with remitted mood disorders. Combinations of these factors might be useful for predicting a BD diagnosis among the mood disorders in a clinical setting.