A new study shines a light on depression in the workplace, suggesting that psychological stress at the office - or wherever people earn their paychecks - can make it more difficult for depressed workers to perform their jobs and be productive.

"There is a large economic cost and a human cost," said study lead author Debra Lerner, Ph.D., director, Program on Health, Work and Productivity, Institute for Clinical Research and Health Policy Studies at Tufts Medical Center.

"We need to develop and test programs that directly try to address the employment of people with depression."

The researchers screened 14,268 adult employees and ultimately compared 286 depressed workers to 193 who were not depressed. They recruited participants between 2001 and 2003 from doctors' offices.

The study findings appear in the January/February issue of the American Journal of Health Promotion.

In many cases, the depressed employees had problems at work, Lerner said. "They're often very fatigued and have motivational issues. They also may have difficulty handling the pacing of work, managing a routine, performing physical job tasks and managing their usual workload."

The findings suggest that there is a link between productivity and an employee's ability to control his or her work. "The workplace does play an important part," Lerner said.

Ronald Kessler, a professor in the Department of Health Care Policy at Harvard Medical School, said the study findings "are consistent with a growing body of evidence that depression has important adverse effects on work performance, both absenteeism and on-the-job performance."

Depression has a greater effect on attendance and productivity than the "vast majority" of other health conditions with the exception of musculoskeletal problems and insomnia, he said.

"This evidence has led to the development of several workplace depression screening and treatment programs," he added. "Evaluations are beginning to show that these programs can be cost-effective when implemented carefully in reducing the indirect workplace costs of depression."

What to do? When it comes to depressed workers, "we are going to need more ways to help those who want to continue working to be able to do so and sustain their productivity," Lerner said.