Impact of Biological Rhythm Dysregulation on Quality of Life in Bipolar Disorder: An Outpatient Cross-Sectional Study

Abstract

Background: Biological rhythms disturbances are now known to be significant features of BD and can last beyond the acute phases of BD. But their relationship with functional impairment and metabolic abnormalities in euthymia is not fully understood. The objective was to compare biological rhythm disturbance between euthymic BD patients and healthy controls and to examine its associations with functioning, residual mood symptoms, and metabolic parameters.

Methods: A total of 40 euthymic BD patients and 40 healthy controls were selected for this cross-sectional comparative study. Biological rhythm disturbances were evaluated by means of the Biological Rhythms Interview of Assessment in Neuropsychiatry (BRIAN). Functional impairment was measured with the Functioning Assessment Short Test (FAST) and the Hamilton Depression Rating Scale (HDRS) and Young Mania Rating Scale (YMRS) were used to measure residual mood symptoms. Other anthropometric and metabolic characteristics were also measured. Group comparisons, correlation analyses and the multiple linear regression were carried out.

Results: Euthymic bipolar disorder (BD) patients demonstrated significantly higher BRIAN scores (44.20 ± 3.83 vs. 19.93 ± 2.08; p<0.001) and FAST scores (29.30 ± 3.31 vs. 10.03 ± 1.42; p<0.001) than healthy controls. Residual depressive and manic symptoms were significantly greater in the BD group. Patients also exhibited higher fasting blood glucose, triglycerides, systolic and diastolic blood pressure, and lower HDL cholesterol. Biological rhythm disturbance correlated significantly with functional impairment, residual mood symptoms, and metabolic parameters. Multiple linear regression identified FAST score (β=0.801, p<0.001), HDRS score (β=0.296, p=0.001), and fasting blood glucose (β=0.184, p=0.018) as independent predictors of biological rhythm disturbance.

Conclusions: Biological rhythm disturbances persist in euthymic bipolar disorder despite symptomatic remission and are associated with functional impairment, residual mood symptoms, and metabolic abnormalities. Functional impairment, residual depressive symptoms, and fasting blood glucose emerged as independent predictors of biological rhythm disturbance. These findings support the clinical importance of biological rhythm assessment and reinforce the need for routine functional and metabolic evaluation during the long-term management of bipolar disorder.