Psychosocial factors at work and risk of depression: a systematic review of the epidemiological evidence

Jens Peter Ellekilde Bonde ^1*

¹ Århus University hospital, Denmark

^* To whom correspondence should be addressed. E-mail: jpbon{at}as.aaa.dk.

Accepted 31 January 2008

Abstract

OBJECTIVES: Major depression is a leading cause of psychiatric morbidity. Psychosocial factors at the workplace may influence the occurrence of this disorder, but evidence so far remains circumstantial. This paper reviews follow-up studies addressing the risk of major depression and depressive symptoms relative to psychosocial stressors in the working environment and evaluates the evidence of causality.

METHOD: Follow-up studies were identified by a systematic Medline search combining search terms for the outcome and measures of job-related psychosocial factors. The quality of the studies was evaluated by twenty-two criteria related to their potential for bias and confounding.

RESULTS: Sixteen company or population-based studies including some 63,000 employees were identified. Validated multi-item scales were used to measure perceived psychosocial stressors in most of the studies. Major depression was defined by clinical criteria in seven studies and by symptom scales were used in another seven studies. The follow-up period ranged from one to 13 years. The prevalence of depressive disorder varied substantially, which points to a high degree of study heterogeneity. The adjusted relative risk for onset of a major depressive episode according to job stressors spanned from 0.5 to 1.5 in 44 of a total of 61 reported associations with various dimensions of psychosocial factors. Associations were strongest and most consistent for job strain defined as high-demand and low decision latitude among men. Most studies shared common limitations such as lack of independent measures of exposure and outcome and potential confounding. Although a meta-analysis would technically be possible, heterogeneity across the studies as evident by much variation in the depression prevalence made such an approach unfeasible.

CONCLUSION: This review provides rather consistent findings indicating that perception of adverse psychosocial factors at the workplace is related to an elevated risk of subsequent onset of depressive symptoms or a major depressive episode, but several methodological limitations preclude causal inference. Studies that implement objective measures of job stressors or independent outcome ascertainment are warranted.