Association Between Gut Microbiota and Depressive Symptoms: A Cross-Sectional Population-Based Study in South Korea.

OBJECTIVE: This study aimed to investigate the association between gut microbiota and depressive symptoms in a large population cohort of Korean adults. METHODS: Overall, 1238 participants were included in the study. Participants were categorized into depressed or non-depressed groups, based on the depressive symptoms reported on the Center for Epidemiologic Studies Rating Scale for Depression, with a cutoff score of 16, and their fecal microbiota was profiled using 16S ribosomal RNA gene sequencing. Several alpha and beta diversity measures were also estimated. The association between depressive symptoms and gut microbiota was analyzed using generalized linear models. The inferred function of the metagenomes was compared between the two groups. RESULTS: There were no consistent differences in alpha and beta diversity between the depressed and non-depressed groups. However, the continuous measure of depressive symptoms was inversely associated with one of four measures of alpha diversity (Shannon's diversity, p = .021). We also found a substantial difference between the depressed and non-depressed groups in the Bray-Curtis dissimilarity among the four beta diversity indices ( p = .004). Participants whose depressive symptoms exceeded a clinical cutoff score had a lower relative abundance of the genus Faecalibacterium when compared with controls (coefficient = -0.025, q = 0.047). However, the depressed group had a significantly higher abundance of the genus Oscillospira than did the non-depressed group (coefficient = 0.002, q = 0.023). CONCLUSIONS: Our findings contribute to the identification of potential relationships between the gut microbiota and depressive symptoms and provide useful insights for developing microbiota-based interventions for patients with depressive symptoms.

The mediating effects of working hours, sleep duration, and depressive mood on the association between shift work and the risk of suicidal ideation in Korean workers.

OBJECTIVES: This study aimed to investigate the mediating effects of working hours, sleep duration, and depressive mood on the association between shift work and the risk of suicidal ideation in Korean workers. METHODS: Data from 33,047 workers were obtained from the nationwide cross-sectional Korea National Health and Nutrition Examination Surveys conducted in 2007-2018. Healthy workers without depressive disorders and chronic medical illnesses were included in the current study. Shift work patterns, sleep duration, working hours, depressive mood, and suicidal ideation were assessed using self-reported questionnaires. Multivariate logistic regressions were used to examine the association between shift work and the risk of suicidal ideation. Additionally, mediating studies were conducted to identify the roles of working hours and sleep durations on the association. RESULTS: Compared with daytime workers, shift workers had 1.33 times greater risk of suicidal ideation (OR = 1.33, 95% Cl = 1.17-1.52, p < 0.001). Specifically, among shift work patterns, fixed-night shift, 24-h rotating shift and irregular rotating shift were associated with the risk of suicidal ideation when compared with daytime workers (irregular rotating shift: OR = 1.92, 95% Cl = 1.29-2.86, p = 0.001; fixed-night shift: OR = 1.75, 95% Cl = 1.32-2.31, p < 0.001; 24-h rotating shift: OR = 1.58, 95% Cl = 1.06-2.36, p = 0.024). In the mediating study, working hours, sleep duration and depressive mood significantly mediated the relationship between shift work and suicidal ideation (direct effect: ß = 0.019, p = 0.001; indirect effect: ß = 0.004, p = 0.031; total effect: ß = 0.023, p < 0.001). CONCLUSION: This study revealed that shift workers had a greater risk of suicidal ideation. The patterns significantly associated with suicidal ideation were irregular rotating, fixed-night, and 24-h rotating shifts. The pathway analysis revealed serial mediating effects of working hours, sleep duration, and depressive mood on the association between shift work and suicidal ideation.

Association Between Subjective-Objective Discrepancy of Sleeping Time and Health-Related Quality of Life: A Community-Based Polysomnographic Study.

OBJECTIVE: This study aimed to investigate the existence of a difference in quality of life (QOL) between individuals with and without significant subjective-objective discrepancy (SOD) in total sleep time (TST). METHODS: From the Sleep Heart Health Study 2, 2540 individuals who had completed polysomnography, a morning sleep survey, and the 36-item Short-Form Health Survey (SF-36) were included in the analyses. The participants were classified as normoestimators (estimation of TST <±60 minutes), underestimators (underestimation of TST ≥60 minutes), or overestimators (overestimation of TST ≥60 minutes). The standardized SF-36 QOL scores were compared among the three groups. An adjusted partial correlation analysis was conducted between SOD and QOL. RESULTS: Of the 2540 participants, 1617 (63.7%), 433 (17.0%), and 490 (19.3%) were assigned to the normoestimator, underestimator, and overestimator groups, respectively. The bodily pain and social functioning components of the SF-36 score were significantly lower in the underestimators than in the normoestimators, whereas the physical functioning component was significantly lower in the overestimators than in the normoestimators. The absolute value of SOD in the TST showed a significant negative correlation with the physical and mental components of the SF-36. CONCLUSIONS: QOL was significantly better in the normoestimator than in the other groups and linearly correlated with the absolute value of SOD. This study suggests that a high prevalence of positive and negative sleep misperception in a community population can be a potential factor associated with poor QOL and potential comorbidities.

Insomnia, Anxiety, and Depression in Patients First Diagnosed With Female Cancer.

OBJECTIVE: This study evaluated whether insomnia, anxiety, and depression differ by type of gynecological or breast cancer. METHODS: From September 7, 2011, to July 14, 2015, this study included 232 patients who were diagnosed with gynecological or breast cancer for the first time. The severity of insomnia, anxiety, and depression was measured with the National Cancer Center Psychological Symptom inventory (NCC-PSI), a self-reported scale, at the first outpatient visit after surgery. Multivariate logistic regression analyses were used to identify which diagnosis was associated with significant symptom levels. RESULTS: Patients with ovarian cancer and breast cancer reported more severe insomnia and problems with daily life compared with cervical cancer patients. Anxiety symptoms were more distressing among breast cancer patients than cervical cancer patients, and the degree of interference in daily life was severe. Finally, compared to those with cervical cancer, ovarian cancer and breast cancer patients reported more severe depression, and their daily life was disrupted more often than reported by cervical cancer patients. CONCLUSION: Many female cancer patients are suffering distress but are not looking for specialized care. Psychiatric approach in the early stages of cancer diagnosis is needed and will require overcoming the stigmas of mental illness and cancer.

Association between change in sleep duration and posttraumatic stress symptoms in natural disaster victims: the mediating role of resilience.

OBJECTIVE: This study investigated the association between changes in sleep duration after disaster and post-traumatic stress disorder (PTSD) symptoms and the mediating role of resilience on the association. METHODS: Data were collected from 2951 Korean adults who were victims of a natural disaster and did not have any mental or medical illnesses before the event. They completed a long-term survey on changes in life for disaster victims using computer-aided personal interviews. Changes in sleep duration before and one month after experiencing a disaster were assessed using a self-reported questionnaire. Resilience levels and PTSD symptoms were measured using the Brief Resilience Scale and the Impact of Event Scale - Revised, respectively, and more than 33 of the IES-R score items were defined as significant PTSD symptoms. Multivariate logistic regression was used to examine the associations between changes in sleep duration and PTSD symptoms. Additionally, mediating studies were conducted to identify the role of resilience on the association. RESULTS: Compared with participants without significant PTSD symptoms, those with PTSD symptoms were more likely to be older and female (group without significant PTSD symptom: mean age = 56.12 ± 18.70 years, female sex = 49.24%; group with significant PTSD symptoms: mean age = 60.88 ± 15.66 years, female sex = 59.52%). Compared with disaster victims without changes in sleep duration, those who had shorter sleep duration after disaster had a higher risk of significant PTSD symptoms (OR = 2.89, 95% Cl = 2.31-3.62, p < 0.001). In the mediating study, resilience level significantly mediated the relationship between reduced sleep duration and PTSD symptoms (direct effect: ß = 0.208, 95% Cl = 0.166-0.250, p < 0.001; indirect effect: ß = 0.007, 95% Cl = 0.002-0.011, p < 0.001; total effect: ß = 0.215, 95% Cl = 0.173-0.257, p < 0.001). CONCLUSION: This study revealed that individuals with reduced sleep duration after disaster had a higher risk of PTSD symptoms, while those with increased sleep duration did not. In addition, mediating effects of resilience level on the relationship between reduced sleep duration and significant PTSD symptoms were observed.

Association of Sleep Duration and Working Hours with Suicidal Ideation in Shift Workers: The Korean National Health and Nutrition Examination Survey 2007-2018.

OBJECTIVE: This study investigated whether sleep duration and working hours were associated with the risk of suicidal ideation. METHODS: Data from 13,628 shift workers (age ≥19) were obtained from the nationwide cross-sectional Korea National Health and Nutrition Examination Surveys conducted in 2007-2018. We included healthy shift workers without depressive disorders and chronic medical illnesses. Sleep duration, working hours, and suicidal ideation were assessed using a self-reported questionnaire. Logistic regressions were used to examine the association of sleep duration and working hours with the risk of suicidal ideation. We examined interactions between sleep duration and working hours in association with suicidal ideation. In addition, interactions of sex or age were also analyzed. RESULTS: Shift workers sleeping for <6 and ≥10 hours/day were associated with suicidal ideation compared with those sleeping for 7 to <9 hours/day. Individuals working >52 hours/week had a higher risk of suicidal ideation compared with those working ≤40 hours/week. In terms of interaction by sex or age groups in the association between working hours and the risk of suicidal ideation, the relationship was stronger for men than for women and for those aged <45 years than for those aged ≥45 years. CONCLUSION: Shorter or longer sleep durations, and long working hours were associated with a higher risk of suicidal ideation. Under long working hours, male shift workers or those aged <45 years were more vulnerable to suicidal ideation.

Association between genetic variants of the norepinephrine transporter gene (SLC6A2) and bipolar I disorder.

We aimed to investigate the associations between genetic variants of the norepinephrine transporter gene (NET, also known as SLC6A2) and diagnosis of bipolar I disorder. In addition, we examined the relationship between the genetic variants and manic and psychotic symptoms in patients with bipolar I disorder. The three SNPs rs28386840, rs2242446, and rs5569 were genotyped in 326 patients: patients with bipolar I disorder (n = 160) and a control group (n = 166). Subsequently, multivariate logistic regression analysis adjusting for age and sex was conducted to identify independent influences of the SNPs on diagnosis of bipolar I disorder. A possible association between manic and psychotic symptoms and variants of SLC6A2 was also investigated in patients with bipolar I disorder. The rs28836840 SNP in the 5'-UTR of SLC6A2 was significantly associated with bipolar I disorder and with severity of manic and psychotic symptoms in this disorder. Individuals carrying a T allele in the rs28836840 SNP were likely to have a lower risk of bipolar I disorder or lower severity of manic and psychotic symptoms in patients with bipolar I disorder (bipolar I disorder diagnosis: OR = 0.643, 95% Cl = 0.468-0.883, p = 0.006; manic symptoms: ß = -2.457, 95% Cl = -4.674 ~ -0.239, p = 0.031; psychotic symptoms: ß = -2.501, 95% Cl = -4.700 ~ -0.301, p = 0.027). For the rs2242446 and rs5569 SNPs, there were no significant differences between patients with bipolar I disorder and those without. Our results revealed associations of the rs28386840 SNP with bipolar I disorder diagnosis and with severity of manic and psychotic symptoms. However, the findings reported here require replication in larger samples and various ethnic groups.

Associations of 25-Hydroxyvitamin D Levels and Arthritis with Sleep Duration: The Korean National Health and Nutrition Examination Survey 2008-2014.

PURPOSE: The mean sleep duration of Koreans is 7 hours 49 minutes, which is the lowest among Organization for Economic Cooperation and Development countries. Although vitamin D deficiency and arthritis are considered modifiable factors influencing restorative sleep, mean vitamin D levels are low (17.33 ng/mL) and arthritis is prevalent among Koreans. This study investigated whether vitamin D deficiency and arthritis increase the risk of short sleep duration. PATIENTS AND METHODS: The current study used data from the Korean National Health and Nutrition Examination Survey (KNHANES) for 46,405 Korean adults. Vitamin D levels were measured using a radioimmunoassay kit. Sleep duration and arthritis history were assessed using a self-reported questionnaire. Sleep duration was categorized as optimal (7 to <9 hours/day), short (<7 hours/day), and long (≥9 hours/day). Vitamin D levels were grouped as vitamin D sufficiency (≥20 ng/mL), insufficiency (10-19.99 ng/mL), and deficiency (<10 ng/mL). Multiple imputation was used to compensate for missing data. Multinomial logistic regression was used to examine the associations of vitamin D and arthritis status with sleep duration. The regressions were adjusted for covariates, and each model was adjusted for vitamin D and arthritis. RESULTS: Among these participants, 23,078 (49.73%) and 3518 (7.58%) had short and long sleep duration, respectively; 26,724 (57.59%) and 4349 (9.37%) exhibited vitamin D insufficiency and deficiency, respectively; and 4709 (10.15%) were arthritis patients. Compared with vitamin D sufficiency, vitamin D insufficiency and deficiency were associated with short sleep duration (vitamin D insufficiency group: OR = 1.07, 95% CI = 1.01-1.13; vitamin D deficiency group: OR = 1.13, 95% CI = 1.03-1.24). The presence of arthritis was associated with short sleep duration (OR = 1.14, 95% CI = 1.06-1.22) compared with its absence. The interaction between vitamin D deficiency and the presence of arthritis was significantly associated with short sleep duration. However, long sleep duration was not significantly associated with vitamin D levels or arthritis status. CONCLUSION: Low vitamin D levels and the presence of arthritis were associated with an increased risk of short sleep duration. Additionally, there was a positive interaction effect between vitamin D deficiency and arthritis on short sleep duration.

Vitamin D deficiency and suicidal ideation: A cross-sectional study of 157,211 healthy adults.

OBJECTIVES: Vitamin D deficiency has been reported to be associated with various neuropsychiatric disorders. However, there are few studies addressing deficient vitamin D levels and suicidal ideation. METHODS: Serum vitamin D of 157,211 Korean adult participants were measured using electrochemiluminescence immunoassay. A self-reported questionnaire was used to assess whether participants experienced suicidal ideation. Logistic regression model was used to estimate the odds ratio (OR) of suicidal ideation according to vitamin D levels. The regression was adjusted for a range of covariates. RESULTS: Compared with sufficient vitamin D levels (≥20 ng/mL), deficient vitamin D levels (<10 ng/mL) were significantly associated with the risk of suicidal ideation (OR = 1.138, 95% Cl = 1.027-1.262). However, the OR of suicidal ideation was not significantly different between the vitamin D insufficient group (10-19.99 ng/mL) and sufficient group (≥20 ng/mL) (OR = 0.988, 95% Cl = 0.932-1.047). CONCLUSION: Deficient vitamin D levels were significantly associated with the risk of suicidal ideation. However, the risk of suicidal ideation was not significantly different between the vitamin D insufficient group and sufficient group.

The association of occupational stress and sleep duration with anxiety symptoms among healthy employees: A cohort study.

The aim of this study is to identify occupational stress associated with the development of new-onset anxiety symptoms and the dose-response relationship between sleep duration and the onset of anxiety symptoms. Data from 29,251 healthy employees who had undergone at least two comprehensive health examinations at Kangbuk Samsung Hospital Health Screening Center were analysed. Anxiety symptoms were assessed using the Beck Anxiety Inventory. Occupational stress and sleep duration were measured using a self-reported questionnaire about total sleep time and the Korean Occupational Stress Scale-Short Form (KOSS-SF), respectively. Flexible parametric proportional hazards model used to estimate the hazard ratios. Compared with the groups without case-level anxiety, discomfort in an organizational climate, high job demands, job insecurity, organizational injustice and lack of reward were associated with the onset of case-level anxiety. Compared with less than 6 hr of sleep per day, the beneficial level of sleep duration was 7 ≤ to <9 hr a day. Almost all subscales of job stress were associated with the development of anxiety symptoms. In addition, the efficacious level of sleep duration for reducing the onset of future anxiety symptoms was 7 ≤ to <9 hr a day.

The Relationship between Serum Vitamin D Levels, C-Reactive Protein, and Anxiety Symptoms.

OBJECTIVE: The aim of study is to investigate the relationship between serum vitamin D, c-reactive protein (CRP) levels, and anxiety symptoms. METHODS: Serum vitamin D and CRP levels of 51,003 Korean adult participants were collected retrospectively. Anxiety symptoms were assessed using the Korean version of Beck Anxiety Inventory. Logistic regression was used to estimate the odds ratio (ORs) of anxiety symptoms by serum vitamin D and CRP levels. The regression was adjusted for covariates, and each model was adjusted mutually for vitamin D and CRP levels. RESULTS: Compared with sufficient vitamin D levels (≥20 ng/mL), insufficient (10-19.99 ng/mL) and deficient (<10 ng/mL) vitamin D levels were significantly associated with risk of anxiety symptoms. Also, continuous vitamin D levels were negatively associated with the risk of anxiety symptoms. CRP levels did not affect the relationship between vitamin D levels and risk of anxiety symptoms. CONCLUSION: Insufficient (10-19.99 ng/mL) and deficient (<10 ng/mL) vitamin D levels were significantly associated with risk of anxiety symptoms. After adjusting for CRP levels, the results were not changed, and no evidence of interaction between vitamin D and CRP levels was found. CRP levels did not account for the association between vitamin D levels and risk of anxiety symptoms.

The association of physical activity and sleep duration with incident anxiety symptoms: A cohort study of 134,957 Korean adults.

BACKGROUND: Maintaining adequate levels of sleep and physical activity (PA) as self-help for the prevention of new-onset anxiety symptoms is becoming more important. METHODS: A cohort study was performed with 134,957 adults, free of anxiety symptoms at baseline who underwent at least two comprehensive health screening examinations between 2012 and 2017. At baseline, the amount of PA was measured using the International Physical Activity Questionnaire-Short Form and sleep duration per day was assessed using a self-report questionnaire. The study's end point was new-onset anxiety symptoms, defined as a Beck Anxiety Inventory score of ≥19. RESULTS: During 361,969 person-years of follow-up, 5086 participants developed case-level anxiety. Compared with a reference (0-600 METs-min/wk), a U-shaped relationship was observed between PA and case-level anxiety. The most beneficial levels of PA for reducing incident anxiety symptoms were higher in men than women (men: 1800-3000 METs-min/wk HR, 0.88 [95% CI, 0.78-0.81], 3000-6000 METs-min/wk HR, 0.81 [95% CI, 0.70-0.93]; women: 600-1,200 METs-min/wk HR, 0.86 [95% CI, 0.76-0.98]). In comparison with a reference (<6 h), the relationship between sleep duration and case-level anxiety also had a U-shaped pattern. The optimal sleep duration for decreasing the onset of case-level anxiety was 7-8 h, regardless of sex (men: HR, 0.75 [95% CI, 0.63-0.90]; women; HR, 0.61 [95% CI, 0.54-0.70]). LIMITATIONS: PA, sleep duration, and anxiety symptoms were measured using self-report questionnaires. CONCLUSIONS: The results of this study revealed the appropriate levels of PA and total sleep time for reducing incident anxiety symptoms.

Association between work stress and risk of suicidal ideation: A cohort study among Korean employees examining gender and age differences.

Objective The aim of this study was to identify work stress associated with the development of suicidal ideation with a focus on gender and age differences among Korean employees. Methods The data of 95 356 healthy employees aged >18 years who had undergone at least two comprehensive health examinations at Kangbuk Samsung Hospital Health Screening Center, South Korea, were analyzed. Risk of suicidal ideation was assessed using a self-reported questionnaire examining suicidal ideation during the past year. Work stress was measured using the Korean Occupational Stress Scale-Short Form. A Cox proportional hazards model was used to examine relationship between work stress and suicidal ideation. Considering gender and age differences in the association between work stress and suicidal ideation, the data were stratified by gender and age groups. Results During 289 706 person-years of follow-up, suicide ideation was identified in 3 460 participants. For male workers, high job demands and lack of reward were associated with the risk of suicidal ideation in young adults and midlife decade group. Job insecurity was associated with the risk of suicidal ideation in midlife decade and middle-aged and older adulthood. Organizational injustice was associated with the risk of suicidal ideation in middle-aged and older adulthood. Discomfort in an organizational climate was associated with the development of suicidal ideation in all age groups. For female workers, organizational injustice and discomfort in an organizational climate were associated with the risk of suicidal ideation in early adulthood. Conclusion The results suggested that certain work stressors are risk factors of suicidal ideation. Gender and age differences in components of work stress associated with suicidal ideation were also observed.

The Association between Physical Activity and Anxiety Symptoms for General Adult Populations: An Analysis of the Dose-Response Relationship.

OBJECTIVE: The aim of this study is to determine the dose-response relationship between physical activity and anxiety symptoms. METHODS: We included data of 124,434 participants who had comprehensive health-screening examinations from January 1st, 2012, to December 31st, 2016, in Kangbuk Samsung Hospital, Seoul and Suwon, South Korea. We measured the level of physical activity using the International Physical Activity Questionnaire-short form (IPAQ-SF) and estimated anxiety symptoms using the Beck Anxiety Inventory (BAI). BAI scores of 19 and above were defined as cases. Logistic regression was used to analyze the association between physical activity and BAI-defined anxiety. Furthermore, we assessed whether sex differences might affect the relationship between physical activity and BAI-defined anxiety by stratifying our data. RESULTS: Compared with the sedentary group (0-600 METs-min/week), individuals achieving 600-6,000 METs-min/wk had a significantly lower risk of BAI-defined anxiety with a U-shaped relationship in general adults. After stratifying our data by sex, we found that optimal ranges of physical activity were 600-9,000 METs-min/wk for men, but 1,200-3,000 METs-min/wk for women. CONCLUSION: We identified a U- or J-shaped association between physical activity and anxiety symptoms, suggesting an optimal dose and upper limit of physical activity for decreasing anxiety symptoms. Optimal levels and upper limits of physical activity for reducing anxiety symptoms were higher for men than for women.

Gender and age differences in the association between work stress and incident depressive symptoms among Korean employees: a cohort study.

PURPOSE: The aim of this study was to identify gender- and age-specific occupational stress associated with depressive symptoms among Korean employees. METHODS: Data of 73,014 employees aged 18 and above who had undergone comprehensive health examinations at Kangbuk Samsung Hospital Health Screening Center, South Korea, in January 2012 and who were followed up until December 2017 were collected, and 63,959 (participation rate: 87.59%, men: 50,413, women: 13,546) were finally analyzed. A Cox proportional hazards model was used to estimate the hazard ratios and 95% confidence intervals of the relationship between occupational stress and depressive symptoms. In light of gender and age differences in the association between occupational stress and depressive symptoms, interaction and stratification by gender and age groups were tested. RESULTS: During 238,630 person-years of follow-up, case-level depressive symptoms developed in 4227 participants (an incident rate of 1.8%). There were gender differences in the relationship between job stress and incident depressive symptoms. For men, high job demand, job insecurity, lack of reward, and discomfort in their organizational climate were associated with incident depressive symptoms in all age groups. Insufficient job control was associated with the development of depressive symptoms only in midlife and organizational injustice only in early adulthood. For women, the results for high job demand, organizational injustice, and discomfort in an organizational climate were associated with the onset of depressive symptoms from early adulthood to the midlife decade. CONCLUSION: The results suggest gender and age differences in the relationship between occupational stress and incident depressive symptoms.

Psychological and genetic risk factors associated with suicidal behavior in Korean patients with mood disorders.

INTRODUCTION: To prevent suicide, a nationwide important issue in Korea, understanding its etiology is essential. This study aimed to delineate the risk factors for suicidal behavior in mood disorder patients in Korea. METHODS: 216 patients with mood disorders were recruited. We measured suicidal ideation (SI) and suicide attempt (SA) history and the association of six gene polymorphisms with SB: COMT (rs4680), HTR1A (rs6295), TPH1 (rs1800532), BDNF (rs6265), SLC1A3 (rs2269272), and SLC1A2 (rs4755404). RESULTS: Patients in the high-SI and SA groups reported more severe depressive, hopelessness, and anxiety symptoms and lower resilience and used less social support-seeking coping than those in the non-significant SI and non-SA groups. Multivariate logistic analysis revealed that depressive disorder, depressive symptoms, poor social support, and less social support-seeking coping were significant independent predictors of suicidal ideation. After adjustment for covariates, age, alcohol consumption, and the rs4680 AA genotype in the COMT gene were associated with suicide attempt. LIMITATIONS: The modest sample size and a relatively few candidate genes are limitations of the study. In addition, there is no normal control group and the retrospective evaluation of SA limits the interpretation of the causal relationship with factors affecting SA. CONCLUSIONS: Suicidal behavior in Korean patients with mood disorders may be associated with younger age, alcohol consumption, depressive symptoms, poor social support, less social support-seeking coping, and the COMT rs4680 Met/Met genotype.

Weekend catch-up sleep is independently associated with suicide attempts and self-injury in Korean adolescents.

The current study aims to determine the associations of insufficient sleep with suicide attempts and self-injury in a large, school-based Korean adolescent sample. A sample of 4553 middle- and high-school students (grades 7-10) was recruited in this study. Finally, 4145 students completed self-report questionnaires including items on sleep duration (weekday/weekend), self-injury, suicide attempts during the past year, the Suicidal Ideation Questionnaire (SIQ), and the Beck Depression Inventory (BDI). A multiple linear regression model showed that higher SIQ scores were associated with longer weekend catch-up sleep duration (p=0.009), higher BDI score (p<0.001), and longer time spent in a private educational institute (p=0.025). The multiple logistic regression analysis revealed that longer weekend catch-up sleep duration (p=0.011), higher BDI score (p<0.001), longer time spent in a private educational institute (p=0.046), and poorer academic record (p=0.029) were associated with suicide attempt and self-injury during the past year. The present results suggest that weekend catch-up sleep duration--which is an indicator of insufficient weekday sleep--might be associated with suicide attempts and self-injury in Korean adolescents.

The relationship between psychotic-like experiences and attention deficits in adolescents.

OBJECTIVE: The present study focused on the relationship between psychotic-like experiences (PLEs) and attention deficits in adolescents. METHODS: A total of 2325 students, ages 14-19 years, across eight high schools in the Republic of Korea were recruited. Students performed the computerized Comprehensive Attention Test (CAT), which measures sustained and divided attention, and completed the Eppendorf Schizophrenia Inventory (ESI) and Beck Depression Inventory (BDI). One hundred sixty-six participants were excluded from the present study due to incomplete answers on the ESI; thus, data from 2159 students were included in the final analysis. RESULTS: Higher ESI scores predicted more omission and commission errors in divided-attention tasks after controlling for age, sex, and depressed mood (p = 0.024; p = 0.001, respectively). Attention and speech impairments on the ESI were the most frequent predictors of an increased number of errors in the attention tasks. All four ESI domains predicted the number of commission errors in divided-attention tasks (p < 0.001, p = 0.040, p = 0.046, and p = 0.013, respectively). In the high-risk group for psychosis (ESI ≥ 29), higher scores on the ideas of reference subscale were significantly associated with a higher number of both omission and commission errors in divided-attention tasks (p = 0.006, p = 0.017, respectively). CONCLUSIONS: PLEs during adolescents were associated with impaired attention on the divided-attention task, which demands increased attentional effort. Attention deficits in adolescents prone to psychosis may be related to thought-content disturbances rather than to cognitive and perceptual symptoms.

Relationship between weekend catch-up sleep and poor performance on attention tasks in Korean adolescents.

OBJECTIVE: To investigate the relationship between insufficient sleep and poor attention in Korean adolescents, adjusting for potential confounding factors of depressed mood and habitual snoring. DESIGN: School-based cross-sectional study. SETTING: Eight high schools in 3 cities in the Republic of Korea. PARTICIPANTS: A sample of 2638 urban high school students (42.2% male and 57.8% female; mean [SD] age, 17.3 [0.6] years [age range, 14-19 years]) completed questionnaires and computerized attention tasks during the school term. EXPOSURE: Weekend catch-up sleep. MAIN OUTCOME MEASURES: Self-reported sleep schedules and habits, including sleep duration, bedtime, wake-up time, depressed mood, and habitual snoring. Also measured were numbers of omission and commission errors on computerized attention tasks. RESULTS: The mean (SD) sleep duration on weekdays was 5 hours 42 minutes (1 hour 0 minutes) per day and on weekends was 8 hours 24 minutes (1 hour 36 minutes) per day. The mean (SD) weekend catch-up sleep was 2 hours 42 minutes (1 hour 42 minutes) per day. After adjusting for age, sex, depressed mood (Beck Depression Inventory score, ≥10), habitual snoring, and weekday sleep duration, increased weekend catch-up sleep was significantly associated with more omission and commission errors on sustained attention tasks (P < .001 and P = .03, respectively) and on divided attention tasks (P = .01 and P = .04, respectively). CONCLUSIONS: Increased weekend catch-up sleep as an indicator of insufficient weekday sleep is associated with poor performance on objective attention tasks. Assessment of catch-up sleep and sleep duration may be useful for physicians to evaluate sleep insufficiency and its adverse effects on attention in adolescents.

Influence of the interaction between the serotonin 1A receptor C-1019G polymorphism and negative life stressors on the development of depression.

The current study aimed to investigate the interaction between the serotonin 1A receptor gene (HTR1A) C-1019G polymorphism and recent negative life stressors on depression in a Korean community sample. The HTR1A C-1019G polymorphism was genotyped in 416 community-dwelling Koreans (156 males, 260 females; 44.37 ± 14.67 years old). Lifetime and current major depressive episodes were diagnosed using the Structured Clinical Interview for DSM-IV. The Center for Epidemiological Studies for Depression Scale (CES-D) was self-applied and face-to-face interviews investigating negative life stressors within the last 6 months were also performed. The results indicated that there were significant interactions between the C-1019G polymorphism and negative life stressors on CES-D scores (p = 0.02) as well as on current major depressive episodes (p = 0.002), but not on past major depressive episodes. G carriers alone had higher CES-D scores and more frequently experienced major depressive episodes after stressors. The interaction between the C-1019G polymorphism in HTR1A and recent negative life stressors accounted for current major depressive episodes and depressive symptoms. Our findings suggest that people with this gene variant may be more susceptible to developing depression especially after negative life stressors.