The impact of changes in job strain and its components on the risk of depression

Objectives. We assessed the impact of changes in dimensions of the psychosocial work environment on risk of depression in a longitudinal cohort of Canadian workers who were free of depression when work conditions were initially reported. Methods. Using a sample (n=3735) from the Canadian National Population Health Survey, we examined the effects of changes in job control, psychological demands, and social support over a 2-year period on subsequent depression. We adjusted models for a number of covariates, including personal history of depression. Results. Respondents with increased psychological demands were more likely to have depression over the following 2 years (odds ratio=2.36; 95% confidence interval=1.14, 4.88). This risk remained statistically significant after adjustment for age, gender, marital status, presence of children, level of education, chronic health conditions, subclinical depression when work conditions were initially assessed, family history of depression, and personal history of depression. Conclusions. These results demonstrate that changes in psychological demands have a stronger influence than changes in job control on the onset of depression, highlighting the importance of not assuming an interaction between these 2 components of job strain when assessing health outcomes.