Depression is diagnosed as part of a complete psychiatric or other mental health evaluation. The evaluation includes a review of current and past symptoms, psychiatric and medical history, family history, social history, and substance-use history. In addition, there is an assessment of the current mental status . Although no tests or procedures are available to diagnose depression, in certain circumstances tests may be ordered in addition to a request for a physical examination to exclude any general medical conditions as a cause for the depression. Depending on the circumstances, the clinician may want to obtain collateral information from family members.
Based on the symptoms, history, and mental status a specific diagnosis can be made. The DSM-IV-TR defines a major depressive episode by the following symptoms:
- Depressed mood for most of the day, nearly every day
- A loss of interest or pleasure in activities
- Significant weight loss (not dieting) or weight gain or change in appetite
- Feelings of worthlessness or inappropriate guilt
- Decreased concentration
- Insomnia or hypersomnia (excessive sleep)
- Psychomotor agitation or retardation
- Fatigue or loss of energy.
- Recurrent thoughts of death or suicidal ideation
All symptoms need not be present, except for at least item 1 or item 2. Additional guidelines are available for clinicians to make a diagnosis of major depression; these consider the number of symptoms present.
One feature necessary for a diagnosis is either a reduction in functional capacity (academic, occupational, or social) or significant distress. There are other forms of depression in addition to major depression, such as dysthymic disorder and bipolar depression. Dysthymic disorder is a chronic, “milder” depression, but it can be quite debilitating because of its chronicity. It is less associated with some of the neurovegetative symptoms that characterize major depression.
Bipolar depression is the depressed phase of a condition called bipolar disorder , also known as “manic-depressive disorder.” The features of this depression are the same as in major depression, but the patient has a history of prior manic or hypomanic episodes. As part of the evaluation the clinician screens for a history of mania, because this can affect the treatment choices for bipolar depression.