Biological rhythms in bipolar and depressive disorders: A community study with drug-naïve young adults.

Aim: To assess biological rhythm disruptions among drug-naïve young adults with bipolar disorder (BD), major depressive disorder (MDD), and community controls.

Methods: This was a cross-sectional study nested in a population-based study. BD and MDD were diagnosed using the Structured Clinical Interview for DSM-IV. Biological rhythm disruptions were assessed using the Biological Rhythm Interview of Assessment in Neuropsychiatry (BRIAN).

Results: Two hundred seventeen subjects were assessed (49 BD, 74 MDD, and 94 community controls). Biological rhythm disruption was higher in subjects with BD (40.32±9.92; p<0.001) and MDD (36.23±8.71; p<0.001) than community controls (27.67±6.88). Subjects with BD had a higher BRIAN total score (p=0.028) and higher disruption in sleep/social domains (p=0.018) as compared to MDD. In addition, the BRIAN scores were higher in current MDD, euthymic BD, and BD in current episode group, as compared to community controls.

Limitation: Cross-sectional design. Absence of assessment of biomarkers of biological rhythms.

Conclusion: Bipolar disorder and major depressive disorder are associated with disruption in biological rhythm. In addition, disruption in sleep/social rhythms is higher in subjects with BD when compared to subjects with MDD. We also verified biological rhythm disruption in subjects with BD during euthymic status, but not in remitted MDD. Regulation of biological rhythm may be a means to identify patients with mood disorders and potentially differentiate MDD from BD.