Increases in psychological demands are more important than declines in job control for the onset of depression in Canadian workers—this, a key finding from an Institute for Work & Health (IWH) study that assessed the impact of such changes on the risk of depression.
Major depression is one of the top three causes of disability burden in high income countries. The economic burden of mental illness in Canada was estimated to be $51 billion in 2003. Our study provides evidence that increases in psychological demands at work play an important role in the development or recurrence of this disease—depression has a work-related component, says IWH Scientist Dr. Peter Smith, who led the investigation. The findings were published ahead of print in December by the American Journal of Public Health (Epub 2011 Dec 15; DOI: 10.2105/AJPH.2011.300376).
Despite the substantial burden of depression among working-age adults, few studies have measured changes in psychosocial working conditions in a representative sample of workers and then followed workers over time to measure the subsequent incidence of depression. In his study, Smith addresses this research gap.
Smith examined the effects of changes in job control (the ability to make decisions and use skills at work), psychological demands (the pace and mental intensity of work) and social support on subsequent depression. Using the National Population Health Survey, he looked for these effects among 3,735 Canadians who were ages 25 to 60 in 2000-2001, and who worked at some point in both 2000-2001 and 2002-2003.
Smith found that increases in psychological demands increased the risk of depression over the two years following the change, and the size of this risk was similar to the size associated with family and personal histories of depression. Approximately 10 per cent of the 150 episodes of depression observed in this sample may be attributed, in part, to adverse psychosocial working conditions related to increased psychological demands.
Moving from research to action
Surveys conducted in Europe and North America over the past 20 years have documented an increase in psychological demands perceived by workers, particularly a faster pace of work. Given the potential role of psychological work demands in the origins of depression, Smith believes improved monitoring of psychosocial working conditions in Canada is important.
In 2004, Quebec was the first province to introduce legislation mandating surveys of working conditions every five years that include outcome data on mental health.
Such surveys provide important information on the relationships between work and issues such as mental health at the provincial level, and should be part of a comprehensive primary prevention agenda, says Smith.
The best way to treat depression is to prevent it.