Circadian Rhythms and Depression in Adolescents: A Comparative Analysis of First Episode and Recurrent-Episode Groups.

Circadian rhythm disruptions are a hallmark feature of mood disorders. Patients experiencing acute depressive episodes report noticeable changes in their sleep-wake cycles. This research explains the association between depression and various circadian rhythm metrics, explicitly focusing on adolescents diagnosed with depressive disorders. Adolescence is a critical period marked by significant physiological and psychological changes, making it imperative to understand how mood disorders manifest during this phase. However, there have been minimal specific studies in pediatric populations to determine whether circadian rhythm changes differ between adolescents with first and multiple-recurrent depressive episodes. Our study involved a group of 61 adolescents aged between 13 and 18. We performed a cross-sectional study of a clinical population of patients presenting to a child and adolescent psychiatry clinic diagnosed with depression. Participants were asked to complete self-report evaluations using several tools: the Korean version of the Biological Rhythms Interview of Assessment in Neuropsychiatry (K-BRIAN), the Korean Translation of Composite Scale to Measure Morningness-Eveningness (KtCS), and the Seasonal Pattern Assessment Questionnaire (SPAQ). Tools such as the Children's Depression Inventory (CDI), State-Trait Anxiety Inventory (STAI), and K-Mood Disorder Questionnaire (K-MDQ) were employed for the assessment of clinical characteristics of depression. Based on the frequency of their depressive episodes, participants were bifurcated into two distinct groups: those experiencing their first episode (n = 22, mean age: 15.09 ± 1.44 years) and those with recurrent episodes (n = 39, mean age: 15.95 ± 1.26 years). At first, the two groups' data revealed no significant differences regarding mood or circadian rhythm metrics (CDI: first episode 26.18 ± 10.54 and recurrent episode 25.90 ± 10.59, STAI-S: first episode 56.91 ± 12.12 and recurrent episode 57.49 ± 11.93, STAI-T: first episode 60.36 ± 11.63 and recurrent episode 59.09 ± 12.10, SPAQ-total: first episode 6.59 ± 4.86 and recurrent episode 6.77 ± 5.23, KtCS: first episode 30.32 ± 5.83 and recurrent episode 28.13 ± 7.36). However, we observed significant correlations between circadian rhythm disruptions and depression scales (CDI with SPAQ-weight (r = 0.26), KtCS (r = -0.48), K-BRIAN-sleep (r = 0.58), K-BRIAN-activity (r = 0.64), K-BRIAN-social (r = 0.71), and K-BRIAN-eating (r = 0.40)). These correlations were especially pronounced in the recurrent episode group, suggesting that with the progression and chronicity of depression, the relationship between circadian rhythms and depression becomes more intertwined and evident. In conclusion, especially in adolescents, as the severity and chronicity of depression increase, the interplay between circadian rhythms and mood disorders becomes more pronounced, warranting further research and clinical attention.