Diagnosis of Depression
There are no laboratory tests to diagnose major depressive disorder. Physicians rely on a thorough psychological examination and the elimination of other disorders as diagnoses.
Diagnostic Criteria for Major Depressive Episode
The American Psychiatric Association has established the diagnostic criteria for the evaluation of a major depressive episode, which are reproduced here.
At least five of the following symptoms have been present during the same two-week period and represent a change from previous functioning; at least one of the symptoms is either (1) depressed mood, or (2) loss of interest or pleasure. (Do not include symptoms that are clearly due to a physical condition, mood-incongruent delusions or hallucinations, incoherence, or marked loosening of associations.)
- depressed mood (can be irritable mood in children and adolescents) most of the day, nearly every day, as indicated by subjective account or observation of others
- markedly diminished interest or pleasure in all, or almost all, activities most of the day, nearly every day (as indicated by subjective account or observation of others), and apathy most of the time
- significant weight loss or weight gain when not dieting (e.g., more than 5 percent of body weight in a month), or decrease or increase in appetite nearly every day (in children, consider failure to make expected weight gains)
- insomnia or hypersomnia nearly every day
- psychomotor agitation or retardation nearly every day (observable by others, not merely subjective feelings of restlessness or being slowed down)
- fatigue or loss of energy nearly every day
- feelings of worthlessness or excessive or inappropriate guilt (which may be delusional) nearly every day (not merely self-reproach or guilt about being sick)
- diminished ability to think or concentrate, or indecisiveness, nearly every day (either by subjective account or as observed by others)
- recurrent thoughts of death (not just fear of dying), recurrent suicidal ideation without a specific plan, suicide attempt, or a specific plan for committing suicide
APA. Diagnostic and Statistical Manual of Mental Disorders, 4th ed. 1994. Washington, DC: American Psychiatric Association (APA).
Beck Depression Inventory
In addition to the American Psychiatric Association's diagnostic criteria, physicians often use the Beck Depression Inventory (BDI), a self-report test designed to measure depression. It consists of 21 multiple-choice questions that focus on sadness, guilt, self-esteem, and pessimistic outlook. The test takes about 15 minutes to complete. The following is an example of a test question:
Over the past week:
- I have not felt sad.
- I have felt sad.
- I have not been able to stop feeling sad.
- I have been so sad that I cannot stand it.
While the BDI is useful in assessing mood and thought process, some physicians criticize its inability to measure associated neurovegetative conditions, such as anorexia, overeating, and insomnia. Other tests are done to assess the presence of these conditions.