Abstract
Mood disorders often accompany circadian rhythm abnormalities. The serotonergic system (STS) is related to mood and circadian rhythm. This study aimed to test whether serotonergic neurotransmission, using the loudness dependence of auditory evoked potential (LDAEP), is associated with circadian preference in patients with major depressive disorder (MDD). Depression severity was assessed in 18–65-year-old outpatients (n = 48) using the Beck Depression Inventory scores and Hamilton Depression Rating Scale at baseline. Additionally, various scales, including the Korean version of the Composite Scale of Morningness (K-CSM), Korean version of the Mood Disorder Questionnaire (K-MDQ), and Korean version of the Childhood Trauma Questionnaire (K-CTQ), were used. LDAEP was also measured at baseline. The subjects were divided into three groups according to the circadian preference using total K-CSM scores (morningness (n = 10) vs intermediate (n = 19) vs. eveningness (n = 19)) and two groups according to median based on each K-CSM score, respectively (higher K-CSM (n = 25) vs. lower K-CSM (n = 23)). The bipolarity, suicidality, and age at onset differed among the three groups. Impulsivity, depression severity, suicidality, hopelessness, bipolarity, frequency of emotional abuse, and age at onset differed between the two group divisions. Thus, the STS might serve as the mediator between the circadian system and mood.
Highlights
Mood disorders often accompany abnormalities in circadian rhythms [1,2]
Another study found that evening preference is more prominent in patients with bipolar disorder (BD) than in those with major depressive disorders (MDD), suggesting that circadian rhythm disturbance is a biological marker for BD [2]
The current study revealed that lower central serotonergic activity and more severe childhood maltreatment were interactively associated with an earlier age at onset
Summary
Mood disorders often accompany abnormalities in circadian rhythms [1,2]. Those abnormalities include advanced or delayed circadian rhythm [2]. Some investigators found that patients with depression exhibit differences in circadian preference from the normal population [3]. A recent study found that the group with evening preference had a higher severity of childhood trauma, depression, and bipolarity than the group with morning preference [5,6]. Another study found that evening preference is more prominent in patients with bipolar disorder (BD) than in those with major depressive disorders (MDD), suggesting that circadian rhythm disturbance is a biological marker for BD [2]
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