Workers with high job demands and job strain are at increased risk of sick leave due to mental disorders, reports a study in the August Journal of Occupational and Environmental Medicine, official publication of the American College of Occupational and Environmental Medicine (ACOEM).

Lisa Mater, MMSc, of Karolinska Institutet, Stockholm, and colleagues used data from a Swedish national twin study to examine how rates of sick leave for mental health reasons are affected by psychosocial factors at work. On five-year follow-up of nearly 12,000 workers, the rate of sick leave due to mental disorders was about eight percent. Three-fourths of workers with mental health sick leave were women.

Who's at highest risk

Workers with high job demands were at greater risk of sick leave due to mental disorders. Risk was also increased for workers with job strain, defined as high job demands with low control; and "iso-strain," defined as high demands and low control plus low levels of social support at work.

Workers with multiple unhealthy behaviors also had higher rates of mental health sick leave. Smoking was a significant risk factor, but alcohol use was not. High physical activity level was a protective factor.

Family factors

The increased risks associated with high job demand and job strain were unaffected by familial factors or health behaviors. Familial factors did seem to contribute to the risks associated with low job support, smoking, and unhealthy behaviors.

Mental disorders are a common and costly cause of work disability. In Sweden, mental disorders are the most common reason for sick leave. The study adds to previous evidence that psychosocial conditions at work affect rates of mental health sick leave — and may suggest ways of reducing this risk.

"Interventions to reduce sick leave due to mental disorders that focus on improving the psychosocial work environment, especially reducing high psychosocial job demands, may prove effective," Lisa Mather and coauthors write. They add that that efforts aimed at improving health behaviors only — without also addressing the work environment — may be less likely to reduce mental health sick leave.

Citation — Mather L, Bergstrom G, Blom V, Svedberg P. High job demands, job strain, and iso-strain are risk factors for sick leave due to mental disorders: a prospective Swedish twin study with a 5-year follow-up. J Occup Environ Med. 2015;57(8):858-65