Circadian Rhythm Characteristics in Mood Disorders: Comparison among Bipolar I Disorder, Bipolar II Disorder and Recurrent Major Depressive Disorder

OBJECTIVE: Morningness/eveningness (M/E) is a stable characteristic of individuals. Circadian rhythms are altered in episodes of mood disorder. Mood disorder patients were more evening-type than normal population. In this study, we compared the characteristics of M/E among the 257 patients with bipolar I disorder (BPD1), bipolar II disorder (BPD2) and major depressive disorder, recurrent (MDDR). METHODS: M/E was evaluated using the Korean version of the composite scale of morningness (CS). Factor analysis was done to extract specific elements of circadian rhythm (morning preference, morning alertness, and evening tiredness). The total score and scores for factors and individual items of CS were compared in order to evaluate differences among the three different diagnostic groups. Factor scores of CS were different among the diagnostic groups. RESULTS: BPD1 subjects had a higher score for evening tiredness than BPD2 subjects (p=0.060), and BPD1 subjects had a significantly higher score for morning alertness than subjects with MDDR (p=0.034). This difference was even more profound for the representative item scores of each factor; item 2 of CS for evening tiredness (BPD1>BPD2, p=0.007) and item 5 of CS for morning alertness (BPD1>MDDR, p=0.002). Total score of CS were not different among 3 diagnostic groups. CONCLUSION: Circadian rhythm characteristics measured by CS were different among BPD1, BPD2, and MDDR. BPD2 showed more eveningness than BPD1. MDDR showed less morningness than BPD1. CS would be a reasonable endophenotype associated with mood disorders. More studies with large sample size of mood disorders on M/E are warranted.

Cross Validation of the Korean Translation of Composite Scale(KtCS) to Measure Morningness-Eveningness / 신경정신의학

OBJECTIVES: It is necessary to develop a questionnaire to classify the circadian rhythm for studying circadian rhythms and predicting shift work adaptability. This study attempted to confirm the general applicability of "Korean translation of Composite Scale(KtCS)" by Jin-Sang Yoon et al(1997), a Korean version of Composite Scale(CS) by Smith et al(1989). METHODS: KtCS and Life Habit Questionnaire(LHQ) were administered to 155 nurses(85 rotating shift nurses, 70 nurses on a fixed day schedule) and 247 female university students. We tested the distribution of KtCS scores and then subjects were categorized on the basis of their KtCS scores into evening(E), intermediate(I), and morning(M) types. Cut-off points for these categories were set at the 10th and 90th percentiles. We obtained the results of the internal consistency and the structure of factors of KtCS. We also compared the differences of life habits according to the circadian rhythm types. RESULTS: In both groups, nurses and female university students, the distributions of KtCS scores were negatively skewed but not significantly and the KtCS mean score was not significantly different. In nurses, Cronbach's alpha was 0.836, and three extracted factors were 'preferred times of performance and going to bed', 'rising time' and 'morning alertness'. In female university students, Cronbach's alpha was 0.787, and the same three factors as nurses were confirmed. However, only item 11 was loaded to factor 1 for the nurse group, whereas it was loaded to factor 2 for the student group. Life habits significantly differed among the three circadian rhythm types. The time of perceived peak alertness(mental and physical) was the latest in the E-type. The quality of academic performance during the morning was the highest in the M-type, and during the evening it was the highest in the E-type, but during the afternoon there was no significant differences among the three types. The bedtime and the rising time were latest in E-type, but the sleep lengths were not significantly different among the three types in both groups. CONCLUSIONS: The psychometric properties of KtCS in nurses were very similar to those of female university students and the previous findings of Jin-Sang Yoon et al(1997). This result supports that KtCS can be generally applied.

A Preliminary Study on the Korean Translation of Composite Scale(KtCS) to Measure Morningness: Eveningness / 신경정신의학

OBJECT: The Composite Scale by Smith et al. has been proposed as an improved measure of momingness-eveningness. This study attempted to endorse that a Korean translation of Composite Scale(KtCS) can be useful to differentiate people according to circadianrhythm types. METHOD: KtCS and Life Habit Questionnaire(LHQ) were administered to 561 university students. LHQ consisted of items questioning sleep habits on weekdays(bedtime, rising time and sleep length), the time of perceived peak alertness(mental and physical), time of perceived peak performance(mental, physical and academic), and quality of academic performance during the morning, afternoon and evening. Subjects were categorized on the basis of their KtCS scores into evening(I) types, intermediate(I) types, and morning(M) types. The cut-off points for these categories were set at the 10th and 90th percentiles. In addition 7 I-type and 7 M-type subjects were selected from the student population who had participated in the previous survey and then, oral temperature of each subject was taken every hour torn 08 : 00 to 22 : 00. To assess both the internal and the external measurement properties of KtCS, descriptive statistics, reliability and validity were examined. RESULTS: The distribution of KtCS scores was significantly, negatively skewed. The KtCS scores closest to the 10th and 90th percentiles were 26 and 41 respectively. The split-half reliability(. 85), test-retest reliability( .91), and internal consistency(Cronbach alpha, .82) were obtained above the expected. Inter-item correlations were all positive and ranged from .10-.59 with a mean of .25. Item-total correlations varied from .33 to .63 with a mean of .45. Common factor analyses confirmed three factors: preferred times of performance and going to bed, arising time, and morning alertness. The validity of KtCS was further demonstrated through strong relationships between the scale and external criteria.4 discernable difference in oral temperature between the M-type and the type across morning to evening provided additional evidence for validity of the scale. CONCLUSIONS: The results would suggest the possibility that KtCS can be employed as a tool for selection of I-type people or M-type people. It is as yet, however, uncertain that KtCS might be suitable to select people for night shiftwork because the subjects of this study are limited to university students. Therefore, future research among varying types of people are required to endorse this study.