Difference in the regulation of biological rhythm symptoms of Major depressive disorder between escitalopram and mirtazapine

Biological rhythm plays an important role in major depressive disorder (MDD). The efficacy of antidepressant in biological rhythm remains unclear. This study is designed to explore the efficiency of escitalopram and mirtazapine in improving circadian rhythm, diurnal mood variation(DMV) and daily activity in MDD patients. Four-hundred and fifty participants diagnosed with MDD were randomized to receive treatment with escitalopram (TWE), treatment with mirtazapine (TWM) or treatment as usual (TAU). Biological rhythm symptoms were assessed by relevant biological subscale in the Hamilton depression scale (HAMD) and the quick inventory of depressive symptomatology self-report (QIDS). The participants were assessed by trained evaluators at baseline and week 2, 4, 6 and 8. The differences of HAMD score among TWE(58%, 69%, 72%), TWM(56%, 64%, 76%) and TAU(49%, 57%, 68%) were significant(P<0.05). But the differences were significant only in patients without DMV; (2) Sleep rhythm items (difficulty falling asleep and early-wake) were significantly improved in TWM (P <0 .05) for both HAMD and QIDS. Decreased appetite and weight were significantly improved in TWM (P<0 .05) for both scales. (3) For daily activity-related items, feeling slowed down and concentration were significantly improved in TWE. And the retardation was significantly improved in TWE and in TWM. Both escitalopram and mirtazapine have superior anti-depressive effect, especially for MDD patients without DMV. Escitalopram was significantly more effective in daily activity, feeling slowed down and concentration difficulty, while mirtazapine was significantly more effective in improving sleep, appetite and weight of MDD.