• Depressed people often feel worthless or guilty and may consider suicide if untreated.woman in solutude and depression image by Allen Penton from Fotolia.com
  
  Depression is a relatively common disorder in which a person loses interest in activities, withdraws from others, and feels sad, hopeless or worthless. It is important to assess patients for depression, as severely depressed people are at risk for suicide. Clinicians often use self-administered questionnaires to help diagnose and treat depressed patients, although they also interview and observe patients as part of the process.
  
  

Beck Depression Inventory

• The Beck Depression Inventory is a self-administered assessment tool. The medical practitioner gives the patient this questionnaire, which contains 21 questions. The patient may choose from a scale of 1 to 4 to indicate how often he experiences the symptom listed in each question. This tool is not a diagnostic tool, according to Real Depression Help. It is used primarily to determine the severity of symptoms a depressed patient is experiencing so that the clinician can prescribe appropriate treatment.
  
  

Zung Self-Rating Depression Scale

• The Zung Self-Rating Depression Scale is a self-administered tool used to assess depression symptoms in patients who already have been diagnosed with depression. This questionnaire consists of 20 questions which address four major components of depression: pervasiveness, physiological symptoms such as extreme fatigue, other problems and psychomotor activities such as restlessness or slowed movement.
  
  

Cornell Scale for Depression in Dementia

• The Cornell Scale for Depression in Dementia is designed for assessing depression in older people, especially those who lack communication or cognitive skills. The clinician administers this assessment by asking 19 questions of an elderly person's caregiver related to the patient's mood and behavior. The clinician then briefly interviews the elderly person and observes her. If there are discrepancies between the caregiver's report and the clinician's observations, the clinician follows up with the caregiver to determine the source of the discrepancy. This tool allows clinicians to diagnose depression in elderly persons via observation.