People who feel chronically stressed on the job may face an increased risk of depression, a large study suggests.

Researchers found that among more than 24,000 working Canadian adults, nearly 5 percent had suffered from major depression in the past year. Those under heavy stress at work appeared to be at particular risk, according to findings in the American Journal of Public Health.

A number of studies have found health risks associated with chronic job stress, including high blood pressure and heart disease, as well as depression. However, the depression studies have been limited to either certain occupations or single companies, noted Dr. Emma Robertson Blackmore, the lead author of the new study and an assistant professor of psychiatry at the University of Rochester Medical School in New York.

This study confirms and extends past research, she told Reuters Health, because it looked at a large, general population and used more-stringent criteria to gauge participants’ depression.

Past studies have relied on questionnaire responses. Participants in the current study underwent diagnostic interviews for depression.

Overall, Robertson Blackmore and her colleagues found, men who reported high job strain were more than twice as likely to suffer depression as men who were low on the job-strain scale. “High job strain” is defined as work that is demanding but leaves people little independence or decision-making authority.

Among women, the picture was somewhat different. Only one component of job strain - lack of decision-making authority - was related to depression. It’s not clear why this difference between men and women emerged, Robertson Blackmore said, but it may have to do with the types of jobs many women take.

Women are more likely than men to take part-time jobs to balance work and family, she and her colleagues note.

However, one measure of job stress - lack of support from co-workers and supervisors - was related to depression in both men and women.

The findings point to a need for depression prevention in the workplace, according to the researchers. Offering workers opportunities for training in new skills, for example, might help relieve one source of job stress, Robertson Blackmore noted.

She also pointed to a government study published just last week that found that workers and employers alike could benefit from better depression screening and treatment. Among employees at 16 large companies who screened positive for depression, those who got extra help from their job’s health plan - phone calls from “care managers” who helped guide the employees through treatment - had greater improvements in their symptoms.

They were also more productive on the job than their co-workers who received standard care, working an average of 2 more hours per week over the course of a year.

SOURCE: American Journal of Public Health, November 2007.