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ObjectiveDelayed sleep phase disorder (DSPD) is a condition in which patients often fall asleep some hours after midnight and have difficulty waking up in the morning. Circadian chronotype questionnaires such as Horne-Östberg Morningness-Eveningness Questionnaire (MEQ) and Basic Language Morningness (BALM) scale have been used for screening for DSPD. This study was to evaluate these two chronotype questionnaires for screening of DSPD.MethodsThe study samples were 444 DSPD and 438 controls. Cronbach's alpha coefficient was calculated to evaluate for internal consistency. An exploratory factor analysis was conducted using principal-axis factoring. The diagnostic performance of a test was evaluated using Receiver Operating Characteristic (ROC) curve analysis. A discriminant function analysis was also performed.ResultsFor internal consistency, Cronbach's alpha of 0.898 for BALM was higher than the 0.837 for MEQ, though both have acceptable internal consistency. BALM has better construct validity than the MEQ because some MEQ items measure different dimensions. However, when we evaluated the efficiency of two questionnaires for DSPD diagnosis by using the ROC curve, the BALM was similar to the MEQ. In a discriminant analysis with the BALM to classify the two groups (DSPD vs. normal), 6 items were identified that resulted in good classification accuracy. Upon examination of the classification procedure, 94.2% of the originally grouped cases were classified correctly.ConclusionThese findings suggest that the BALM has better psychometric properties than the MEQ in screening and discriminating DSPS.

People called night owls habitually have late bedtimes and late times of arising, sometimes suffering a heritable circadian disturbance called delayed sleep phase syndrome (DSPS). Those with DSPS, those with more severe progressively-late non-24-hour sleep-wake cycles, and those with bipolar disorder may share genetic tendencies for slowed or delayed circadian cycles. We searched for polymorphisms associated with DSPS in a case-control study of DSPS research participants and a separate study of Sleep Center patients undergoing polysomnography. In 45 participants, we resequenced portions of 15 circadian genes to identify unknown polymorphisms that might be associated with DSPS, non-24-hour rhythms, or bipolar comorbidities. We then genotyped single nucleotide polymorphisms (SNPs) in both larger samples, using Illumina Golden Gate assays. Associations of SNPs with the DSPS phenotype and with the morningness-eveningness parametric phenotype were computed for both samples, then combined for meta-analyses. Delayed sleep and "eveningness" were inversely associated with loci in circadian genes NFIL3 (rs2482705) and RORC (rs3828057). A group of haplotypes overlapping BHLHE40 was associated with non-24-hour sleep-wake cycles, and less robustly, with delayed sleep and bipolar disorder (e.g., rs34883305, rs34870629, rs74439275, and rs3750275 were associated with n=37, p=4.58E-09, Bonferroni p=2.95E-06). Bright light and melatonin can palliate circadian disorders, and genetics may clarify the underlying circadian photoperiodic mechanisms. After further replication and identification of the causal polymorphisms, these findings may point to future treatments for DSPS, non-24-hour rhythms, and possibly bipolar disorder or depression.

ObjectiveThe aim of this study was to develop a culturally sensitive instrument that addressed how individuals express and experience depression to detect this disorder in Koreans. We also assessed the validity, reliability, and diagnostic utility of this scale (Lee and Rhee Depression Scale; LRDS).MethodsThe sample consisted of 3,697 normal adults selected from 12 administrative districts (Do) and 448 Korean patients diagnosed with depression using the Structured Clinical Interview for DSM-IV Axis I disorders (SCID-I). Reliability was calculated using Cronbach's α. Construct validity, discriminant validity, and concurrent validity were also measured. Receiver-operator-characteristic (ROC) analysis was employed to evaluate diagnostic efficiency.ResultsThe LRDS was found to be a reliable instrument (Cronbach's α=0.95) consisting of six factors: negative thinking about the future, negative thinking about the self, worry and agitation, depressed mood, somatization, and loss of volition. Comparison of LRDS scores discriminated the group of patients with depression from the normal individuals in the control group. The measure showed good concurrent validity in that scores were significantly and strongly correlated with scores on established scales such as the Beck Depression Inventory (BDI), the Hamilton Depression Rating Scale (HAM-D), and the D scale of the Minnesota Multiphasic Personality Inventory-second edition (MMPI-2). Diagnostic efficiency was 77.7%, and the cut-off scores were 65 for males and 70 for females.ConclusionTo our knowledge, this is the first study to develop a depression-screening scale on the basis of Korean patients' complaints about the disorder. As a culturally sensitive tool, the LRDS will be useful in clinical and research settings in Korea.

These results suggest that GST gene polymorphisms do not confer increased susceptibility to TD in patients with schizophrenia but TD severity might be related with GST-P1 variants.