The present findings coincide with our hypothesis that circulating mtDNA contributes to the inflammation in MDD. Further studies are needed to conclude whether plasma mtDNA would be a biomarker of mood disorders.

Japanese teachers are mentally and physically burdened with various work stressors. This cross-sectional study examined the relationship between depressive symptoms and perceived individual level occupational stress including role problems among Japanese schoolteachers. This study included 1,006 teachers working in public schools in a Japanese city. The Japanese version of Zung’s Self-Rating Depression Scale (SDS) was used to evaluate depressive symptoms, and the Generic Job Stress Questionnaire was used to evaluate occupational stress and three measures of social support. Subjects with SDS scores of more than 50 were categorized into the “depressive group.” We examined the relationship between depressive symptoms and perceived individual level occupational stress using multiple logistic regression analyses. A total of 202 (20.1%) teachers belonged to the depressive group. We found that high role ambiguity, high role conflict, high quantitative workload, and low social support from family or friends were significantly related to depressive symptoms. To moderate role ambiguity and role conflict experienced by teachers, it is necessary to clarify the priority order of teachers’ work. Furthermore, it is necessary to reduce workload by focusing on the content of teachers’ work and the setting of education itself. Focusing on these elements will reduce teachers’ depressive symptoms.

BackgroundDiagnostic biomarkers of major depressive disorder, bipolar disorder, and schizophrenia are urgently needed, because none are currently available.MethodsWe performed a comprehensive metabolome analysis of plasma samples from drug-free patients with major depressive disorder (n=9), bipolar disorder (n=6), schizophrenia (n=17), and matched healthy controls (n=19) (cohort 1) using liquid chromatography time-of-flight mass spectrometry. A significant effect of diagnosis was found for 2 metabolites: nervonic acid and cortisone, with nervonic acid being the most significantly altered. The reproducibility of the results and effects of psychotropic medication on nervonic acid were verified in cohort 2, an independent sample set of medicated patients [major depressive disorder (n=45), bipolar disorder (n=71), schizophrenia (n=115)], and controls (n=90) using gas chromatography time-of-flight mass spectrometry.ResultsThe increased levels of nervonic acid in patients with major depressive disorder compared with controls and patients with bipolar disorder in cohort 1 were replicated in the independent sample set (cohort 2). In cohort 2, plasma nervonic acid levels were also increased in the patients with major depressive disorder compared with the patients with schizophrenia. In cohort 2, nervonic acid levels were increased in the depressive state in patients with major depressive disorder compared with the levels in the remission state in patients with major depressive disorder and the depressive state in patients with bipolar disorder.ConclusionThese results suggested that plasma nervonic acid is a good candidate biomarker for the depressive state of major depressive disorder.

Insomnia among workers reduces the quality of life, contributes toward the economic burden of healthcare costs and losses in work performance. The relationship between occupational stress and insomnia has been reported in previous studies, but there has been little attention to temperament in occupational safety and health research. The aim of this study was to clarify the relationships between temperament, occupational stress, and insomnia. The subjects were 133 Japanese daytime local government employees. Temperament was assessed using the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego-Auto questionnaire (TEMPS-A). Occupational stress was assessed using the Generic Job Stress Questionnaire (GJSQ). Insomnia was assessed using the Athens Insomnia Scale (AIS). Stepwise multiple logistic regression analyses were conducted. In a stepwise multivariate logistic regression analysis, it was found that the higher subdivided stress group by “role conflict” (OR = 5.29, 95% CI, 1.61–17.32) and anxious temperament score (OR = 1.33; 95% CI, 1.19–1.49) was associated with the presence of insomnia using an adjusted model, whereas other factors were excluded from the model. The study limitations were the sample size and the fact that only Japanese local government employees were surveyed. This study demonstrated the relationships between workers’ anxious temperament, role conflict, and insomnia. Recognizing one’s own anxious temperament would lead to self-insight, and the recognition of anxious temperament and reduction of role conflict by their supervisors or coworkers would reduce the prevalence of insomnia among workers in the workplace.

Most teachers have a high risk of work-related stress and mental disorders. Drunken driving and hazardous alcohol consumption (HAC) among teachers are social problems. Gender differences among teachers in burnout, occupational stress, self-efficacy and job satisfaction were reported. This study aimed to clarify gender differences in the relationships between perceived individual-level occupational stress and HAC among Japanese teachers. A cross-sectional study was conducted in 2013 and a total of 723 male and 476 female teachers remained after excluding non-drinkers. Perceived individual-level occupational stress was assessed using the Generic Job Stress Questionnaire. HAC was defined as ethanol consumption greater than or equal to 280 g in 1 week for male teachers, and greater than or equal to 210 g for female teachers. Multiple logistic regression analyses were conducted. HAC was identified in 16.6% of male and 12.4% of female teachers. The average ages (± standard deviation: SD) of male and female teachers were 46.9 ± 10.9 years and 39.9 ± 12.3 years, respectively. Schoolteacher was the most common position classification among male (48.7%) and female teachers (86.3%). For those with a moderate level of stress, “social support from supervisors” was associated with HAC among males (odds ratio [OR] = 0.43, 95% confidence interval [CI] = 0.23–0.8), whereas for female teachers with a high level of stress, “variance in workload” was associated with HAC (OR = 2.09, 95% CI = 1.04–4.24), using an adjusted model. This study showed that moderate social support from supervisors was negatively related to HAC among male teachers, and high variance in workload was positively related to HAC among female teachers. Gender differences need to be considered when developing HAC prevention strategies for teachers.