The relationship between morningness-eveningness and mood symptoms and quality of life in euthymic state of mood disorders: Results from a prospective observational cohort study

Abstract

BackgroundThe clinical importance of morningness-eveningness, especially in mood disorders, is prevailing. The differential relation of chronotype with diagnoses of early-onset mood disorders, mood symptoms, anxiety, and quality of life was evaluated. MethodsEarly-onset mood disorder patients [n = 419; 146 major depressive disorder (MDD); 123 bipolar I disorder (BDI); 150 bipolar II disorder (BDII)] from the Mood Disorder Cohort Research Consortium were assessed for chronotype using the composite scale for morningness (CSM) and its association with clinical variables obtained during the clinician-verified euthymic state. ResultsThe mean total CSM of BDI was significantly higher than MDD and BDII (p < 0.001). In all types of mood disorders, higher total CSM was associated with lower Quick inventory of depressive symptomatology (p < 0.005) and higher WHO quality of life (p < 0.005). Such negative correlations between the total CSM and Montgomery-Asberg depression rating were significant in MDD and BDI (p < 0.05) and marginally significant in BDII (p = 0.077). CSM was a significant contributor to quality of life in BDI (p < 0.001) and BDII (p = 0.011), but it was not for MDD. LimitationsThe defined ‘euthymic state’ that may not fully reflect the remission of episode; limited generalizability due to clinical characteristic of early-onset mood disorder; the disparity between diurnal preference measured by the CSM and chronotype; possible effects of the last mood episode polarity and medication; and, lack of control group. ConclusionLess eveningness was associated with less severe depressive symptoms and better quality of life. This suggests that morningness may reduce residual depressive symptoms and recover function of patients.