Objective: To assess associations between the main, nonlinear, and interactive effects of the demand-control-support (DCS) model and the cortisol/dehydroepiandrosterone sulfate (DHEA-S) ratio, a biomarker of psychophysical well-being.
Methods: Subjects were 596 employees from all occupational levels of a German airplane manufacturing plant. Multiple regression models controlling for age and gender were computed separately for employees with (n = 103) and without (n = 493) management responsibilities.
Results: Among employees without management responsibilities, the dimensions of the DCS model did not predict the cortisol/DHEA-S ratio. In contrast, among employees with management responsibilities, both linear and nonlinear job demand effects explained a substantial fraction of the cortisol/DHEA-S variance. Increasing levels of job demands were associated with decreasing cortisol/DHEA-S ratios (linear effect) with the quartile of moderately high levels of job demands representing an optimal level. Furthermore, we observed a significant nonlinear effect with job control and a significant interaction between job demands and job control among employees with management responsibilities. These results suggest a beneficial effect associated with moderate levels of job control. This may be due to a buffering effect against adverse levels of job demands (interactive effect) and the independent association with decreased cortisol/DHEA-S ratios (nonlinear effect).
Conclusion: This is the first study that provides evidence that the DCS model is associated with the cortisol/DHEA-S ratio. Among employees with management responsibilities, moderate levels of job control may help managers to cope effectively with job demands and may induce a favorable cortisol/DHEA-S ratio.