What Is the Zung Self-Rating Depression Scale?

Created by psychiatrist William Zung, a Duke University professor, the Zung self-rating depression scale is one of a handful of questionnaires used by therapists and clinicians to gauge the level of patients' depressive disorders. Respondents answer "a little of the time," "some of the time," "a good part of the time" or "most of the time" to the test's 20 statements. The Zung test then quantifies the score in four brackets of depression, in a range from normal to severely depressed. This method is used in several countries in numerous languages.

The statements to which patients respond in the Zung self-rating depression scale, also known as a mood inventory, are evenly divided between positively and negatively constructed descriptive phrases. For instance, the first statement is "I feel down-hearted and blue." The next is "Morning is when I feel the best." This continues until the patient has quantified all 20 statements with his or her level of veracity for each particular sentiment.

Zung designed his test to gauge four modes of depression in average patients. Some statements attempt to quantify the pervasive effect of the disorder; others aim to determine the physiological strain derived from the patient's depressive state. The other types of statements verify if any psychomotor disturbances or agitation is present, such as wringing the hands or biting the nails. The fourth type of statement is a catch-all to see if other problems may exist.

For each statement, the patient tallies a "1" to "4" score, depending on level of agreement. At the end of the test, the sum of all statements is determined. Scores between 20 and 49 indicate a normal level of depressive activity, but 50 to 59 is mildly depressed. A score of 60 to 69 is moderately depressed, and any scores 70 or beyond is considered severely depressed.

Zung, however, did not confine his scale creation to depressive disorders. The Zung self-rating depression scale is one of several tests regularly used to help health professionals determine the proper course of treatment. Another commonly used clinical tool is Zung's self-rating anxiety scale.

For depression alone, there is also a Hamilton rating scale, a Montgomery-Asberg scale, a Beck Depression Inventory, a Beck hopelessness scale, a geriatric depression scale, and a post-natal scale. There is also a test that combines statements about depression and anxiety — two disorders that often appear in concert. Depending on the level of depression, the family history of depression, and even other factors, one or several of these tests could be employed to properly diagnose and treat this disorder.