摘要：Objectives. We addressed whether repeated job strain and low work social support increase the risk of major depressive disorder (MDD). Methods. We used work characteristics from Karasek’s Job Strain model, measured on 3 occasions over 10 years in a cohort of 7732 British civil servants, to predict subsequent onset of MDD with the Composite International Diagnostic Interview. Results. Repeated job strain was associated with increased risk of MDD (odds ratio [OR] = 2.19; 95% confidence interval [CI] = 1.48, 3.26; high job strain on 2 of 3 occasions vs none) in a fully adjusted model. Repeated low work social support was associated with MDD (OR = 1.61; 95% CI = 1.10, 2.37; low work social support on 2 of 3 occasions vs none). Repeated job strain remained associated with MDD after adjustment for earlier psychological distress. Conclusions. Demonstration of an increased association for repeated job strain adds to the evidence that job strain is a risk factor for depression. Recognition and alleviation of job strain through work reorganization and staff training could reduce depression in employees. Major depressive disorder (MDD) has a high prevalence among adults in the general population 1 and is associated with considerable disability 2 and sickness absence. 3,4 This is a burden in both human and economic terms, 5,6 and any measures that could be identified to ameliorate this would be of great benefit. One area in which there is scope for preventive measures is the workplace. Adverse psychosocial work characteristics have been associated with increased risk of depressive symptoms 7,8 and common mental disorder, 9–13 and a meta-analysis of common mental disorder has identified job strain, effort–reward imbalance, and low social support as consistent risk factors. 14 In the job strain model, 15 high demands at work coupled with low control over work (low decision latitude) and low work social support have also been associated with increased risk of cardiovascular disease 16,17 and decreased well-being. 9 The evidence from these studies has been criticized because of (1) reliance on self-report measurement of work characteristics, and (2) outcomes derived from mental health symptom scales that are subject to exposure misclassification and response bias from negative affectivity and common method variance. 18,19 Nevertheless, associations between job strain, low social support, and depression have been found in studies using structured interviews such as the Composite International Diagnostic Interview (CIDI) and the Clinical Interview Schedule, 20–25 in which negative affectivity is reduced. Additionally, job strain has been linked to physician-diagnosed depression 26 and the prescription of antidepressants. 27 However, a systematic review has described the evidence linking the job strain model and depression as inconsistent, and there is a need for studies assessing duration and intensity of exposure to workplace hazards to test potential causal associations. 28 Two analytic strategies could assist this type of study: first, test whether there is any evidence of dose–response associations between number of occasions of exposure to adverse work characteristics and increased risk of depression, and second, examine whether adverse change in work characteristics is longitudinally associated with increased risk of MDD. We employed these 2 strategies using data from the Whitehall II study, a longitudinal occupational study of British civil servants.
