WASHINGTON -- All adults, including pregnant women and new mothers, should be screened for depression as a routine part of health care, a government advisory group recommended Tuesday.

Depression is a common public health problem, and screening simply involves health workers asking about certain symptoms even if patients don't mention them.

The second part of the recommendation from the U.S. Preventive Services Task Force is more difficult -- ensuring systems are in place to properly diagnose and treat people identified through screening.

And the guideline, published by the Journal for the American Medical Association, couldn't determine how often adults should be screened.

Some things to know about depression:

DEPRESSION IS MORE THAN NORMAL SADNESS

Officially called major depressive disorder, depression interferes with people's ability to function in their daily lives and can even lead to suicide. Nearly 7 per cent of U.S. adults experience a depressive episode each year, the National Institute of Mental Health estimates. Symptoms can include persistent sadness, feeling hopeless, difficulty concentrating, problems sleeping and loss of interest in once-pleasurable activities. People sometimes also experience physical symptoms, such as headaches or back pain, which can confuse diagnosis.

NO SINGLE CAUSE

Depression can affect anyone, and there are multiple risk factors. A personal crisis, such as loss of a loved one, sometimes precedes depression, but it also can occur without any obvious trigger. Depression and other mood disorders tend to run in families, and depression frequently accompanies serious physical disorders.

Hormones can play a role, during pregnancy and after a woman gives birth. The task force cited a study that found about 10 per cent of new mothers experienced a postpartum depression episode, more serious and lasting longer than so-called "baby blues."

WHY SCREEN?

Depression can go unrecognized, especially if patients don't seek a diagnosis. Updating 2009 guidelines, the task force reviewed years of research and said Tuesday that screening for depression remains an important part of primary care for adults of all ages. This time around, the guideline separately addresses pregnant and postpartum women, concluding they, too, benefit from screening.

A variety of screening questionnaires are available, such as one that asks how often, over the last two weeks, patients have felt bad about themselves or felt like they're a failure, had little interest in doing things or experienced problems sleeping, sleeping or concentrating.

Still undetermined, the task force said, is how often to screen, given that a person's circumstances and risk could change over time.

Those aren't new recommendations; several other health groups also have long urged depression screening, although there's no data on how often it's done. But the task force says one key is that appropriate follow-up be available to accurately diagnose those flagged by screening -- and then to choose treatments that best address each person's symptoms with the fewest possible side effects.

SCREENING IS A FIRST STEP

Treatment options include psychotherapies such as cognitive behavioural therapy, a variety of antidepressants or some combination. One challenge is that there's little way to predict which patient will respond to which treatment, Dr. Michael Thase of the University of Pennsylvania, who wasn't involved with the task force, said in an accompanying editorial in JAMA. Many antidepressants have modest effects, and typical first-line therapies may not be enough for more severely affected patients, he noted.

Pending a better way to choose, primary care doctors may need to get creative to be sure patients don't abandon treatment, Thase said. He suggested that health workers call to check if patients have filled their antidepressant prescriptions, or trying web-based symptom monitoring to see if they're responding to therapy or need a switch.

A bigger challenge can be finding a specialist to whom primary care doctors can refer their more seriously affected patients, said Dr. Michael Klinkman of the University of Michigan, who also wasn't involved with the task force.

"Either the capacity is not there, or the wait times are so long that a patient who is referred is in limbo for weeks and weeks while they might be fairly sick," said Klinkman, a family physician who works with rural primary care providers to develop needed support systems.