The test: The doctor may ask simple questions, such as "Over the past two weeks, have you felt down, depressed or hopeless?" and "Over the past two weeks, have you felt little interest or pleasure in doing things?" Or, the doctor might use more formal methods. One method is not recommended over the other.

Why the test is performed: To screen adults for signs of depression and other mental health issues. Groups at increased risk are those with other psychiatric disorders, including substance misuse; those with a family history of depression; those with chronic medical diseases; and those who are unemployed or of lower socioeconomic status. Also, women are at increased risk compared with men.

Frequency: It has not been determined how often an individual should be screened. Recurrent screening is most helpful to the groups who are at increased risk.

Abnormal results: Treatment may include antidepressants or specific psychotherapeutic approaches. This may include talk therapy or psychosocial counseling or both. In treating patients ages 18 to 29 years, doctors may want to select a treatment other than an antidepressant because of the increased risk for suicidal behavior associated with the medication. For adults 65 years or older, doctors may want to select a treatment other than antidepressants because of the increased risk for upper gastrointestinal bleeding.

The test: The doctor will always ask about symptoms of depression and check for signs of substance abuse, which may lead to depression. The doctor will perform a physical exam and order blood tests to rule out medical causes for the symptoms.

Why the test is performed: To screen children and adolescents for signs of major depressive disorder and other mental health issues. MDD among youths is associated with serious long-term illnesses and risk of suicide. However, the majority of depressed youths are undiagnosed and untreated. Teen depression can be a response to a life-altering event, such as a death in the family, a result of changing hormones or conflict with peers or family members. Adolescent girls are twice as likely as boys to experience depression. A family history of depression also puts teenagers at greater risk.

Frequency: It has not been determined how often an individual should be screened. Screening is most helpful to the groups who at increased risk. Parents should take their children to be screened if they notice a change in behavior or any symptoms of depression.

Abnormal results: Treating depressed youth with antidepressants is associated with an increased risk of suicide and, therefore, should only be considered if clinical monitoring is possible. Talk therapies are recommended.