Family doctors don't need to screen for depression in adults who aren't showing symptoms, new Canadian guidelines recommend.

On Monday, the Canadian Task Force on Preventive Health Care updated its 2005 guidelines.

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Marc Fignon, left, director of the film The Great Depression, hands out flyers for his film to festival patrons at the Sundance Film Festival. New Canadian screening recommendations do not apply to people with known depression. (Chris Pizzello/Invision/Associated Press)

"Our recommendations highlight the lack of evidence about the benefits and harms of routinely screening for depression in adults," Dr. Michael Joffres, chair of the group's depression guidelines writing group and his co-authors concluded in the Canadian Medical Association Journal. Joffres is also a member of the Faculty of Health Sciences at Simon Fraser University, in Burnaby, B.C.

"In the absence of a demonstrated benefit of screening, and in consideration of the potential harms, we recommend not routinely screening for depression in primary care settings, either in adults at average risk or in those with characteristics that may increase their risk of depression."

It's estimated one in every eight adults meets the criteria for major depression at some point during their lifetime and one in 20 aged 15 or older had in the past 12 months, according to the 2002 Canadian Community Health Survey.

The value of screening didn't hold up for milder cases, the panel said.

They suggested that clinicians stay alert to the possibility of depression, especially in patients that may increase their risk, and to look for it when there are clinical clues such as insomnia, low mood, diminished interest or pleasure in activities and suicidal thoughts.

The recommendations do not apply to people with known depression, with a history of depression or who are receiving treatment for depression.

Depression constitutes a major public health problem, Dr. Roger Bland, of the University of Alberta, said in a journal commentary published with the guidelines, titled, "Why screening for depression in primary care is impractical."

"Although milder cases may require only watchful waiting rather than treatment, about 15 per cent of people with major depression go on to a chronic course, with much residual disability. Family physicians have been criticized for failing to recognize depression. However, studies have shown that many missed cases are those of milder depression, which often remits spontaneously, and that patients with milder forms of depression may experience adverse effects and other complications if the depression is treated."

Bland said the task force did not define "screening." Several standard questionnaires are available ranging from two questions to 10 asking how you feel both physically and mentally.

The Canadian guidelines differ slightly from those in other developed countries.

The U.S. Preventive Services Task Force recommends universal screening where supports exist to ensure follow-up treatment, which is similar to the previous Canadian statement.

In the United Kingdom, the National Institutes for Health and Clinical Excellence recommends a targeted approach, focusing on people with a history of depression rather than general screening. As in Canada, these recommendations do not apply to people with known depression, with a history of depression or who are receiving treatment for depression.

The task force is funded by the Public Health Agency of Canada and the Canadian Institutes of Health Research.