Is there support for curvilinear relationships between psychosocial work characteristics and mental well-being? Cross-sectional and long-term data from the Whitehall II study

Abstract

This study aimed to test whether curvilinearity would add explanatory power to the long-term relationships between job characteristics and mental well-being. The study was based on cross-sectional and longitudinal data from phases 3 and 5 of the Whitehall II sample (N=4154 for job satisfaction and 6000 for context-free mental well-being, mean follow-up 5.8 years). The curvilinear components of the job characteristics were introduced after controlling for the baseline outcome measure, demographic factors, and the linear measures of the job characteristics. The cross-sectional analyses showed only a curvilinear association with the expected U-shape between job demands and context-free mental well-being. The longitudinal analyses showed no curvilinear relationships between the job characteristics and context-free mental well-being. While small non-linear relationships were found between social support and decision latitude and job-related mental well-being, the shape of these relationships was the reverse of that expected. Post hoc analyses revealed that only the positive segment of the relationship between decision latitude and job satisfaction was significant, while both segments of the relationship between social support and job satisfaction were significant. The findings from this study, based on a large sample with high variety in working conditions, provide little support for the assumption of curvilinearity in the long-term relationship between psychosocial working conditions and mental well-being. This has practical implications, as if associations are linear this would indicate that it would be reasonable to take a population (rather than individually targeted) approach to stress management interventions.

Keywords:

• Curvilinearity
• demand–control–support model
• mental health
• Whitehall II
• vitamin model
• work-related stress

The work reported in this paper was supported by the UK Health and Safety Executive. The Whitehall II study has been supported by grants from the Medical Research Council; British Heart Foundation; Health and Safety Executive; Department of Health; National Heart Lung and Blood Institute (HL36310), US, NIH: National Institute on Aging (AG13196), US, NIH; Agency for Health Care Policy Research (HS06516); and the John D. and Catherine T. MacArthur Foundation Research Networks on Successful Midlife Development and Socio-economic Status and Health. The second author is supported by the MRC (Grant number G8802774). We thank all participating Civil Service departments and their welfare, personnel, and establishment officers; the Occupational Health and Safety Agency; the Council of Civil Service Unions; all participating civil servants in the Whitehall II study; all members of the Whitehall II study team.