Synonyms

SDS; Self-rating depression scale; ZSDS; Zung

Description

The Zung Self-Rating Depression Scale (ZSDS) is a 20-item self-report measure of presence and severity of depressive symptoms. Each item describes a symptom of depression, and the respondent is asked to rate the frequency of each symptom using a scale of descriptors: none or a little of the time/some of the time/good part of the time/most of the time (scored from 1 to 4). Ten items are keyed in the positive direction and ten in the negative as a control on response sets. The ZSDS usually takes less than 5 min to complete, depending on the functional status of the patient. It requires an approximately sixth grade reading level, and some versions are in small print which must be considered before use with patients with certain types of impairments. Items are cued to “the past several days,” though the measure may be completed in reference to symptoms experienced at the time of the assessment.

The items of the ZSDS fall into one of four categories: affective, somatic/physiological, psychomotor, and psychological. However, there are no formal subscales within the measure; rather, the ZSDS yields an overall score. An index score for the ZSDS is computed by summing the item raw scores and dividing the total by 0.8, resulting in a range from 25 to 100. An index score of less than 50 is considered to reflect no significant depressive symptomatology, 50–59 mild depression, 60–69 moderate to severe depression, and 70 and above severe depression (Zung 1990).

Historical Background

The ZSDS was developed by Zung (1965) in response to perceived shortcomings of previous depression measures. His intent was a self-administered, brief, and straightforward instrument for indicating the presence and severity of depression. The ZSDS has enjoyed a long history of inclusion in research studies to monitor treatment progress, and it has become a widely used depression measure in clinical settings. The ZSDS has undergone little revision over time, with two slight wording changes appearing in a post-1974 version. In spite of its early origins, the ZSDS includes items which pertain to all of the criteria under category A for Major Depressive Disorder in the current psychiatric diagnostic nomenclature (DSM-V; American Psychiatric Association 2013), though items may not reflect both poles of a given criterion (e.g. loss of appetite is assessed but not increased appetite). It has been translated into at least 30 languages including Spanish, Chinese, Japanese, German, and Greek. Normative data was published for reference by Knight and colleagues in 1983.

Psychometric Data

The ZSDS does not have a manual; however, numerous reliability and validity studies are found in the literature. In their review of reliability findings, Nezu et al. (2000) reported internal consistency alphas ranging from 0.88 to 0.93. A study by McKegney et al. (1988) showed a 1-year test-retest correlation of 0.61 in elderly patients. The ZSDS also demonstrates convergent validity with the Brief Symptom Inventory (Tate et al. 1993) in spinal cord populations. Further, Kerner and Jacobs (1983) obtained a correlation of 0.54 with the Beck Depression Rating Scale (BDI). McDowell’s (2006) review indicated that the instrument correlates 0.55–0.70 with the Depression scale of the Minnesota Multiphasic Personality Inventory (MMPI), and 0.38–0.80 with the Hamilton Rating Scale for Depression (HRSD). His review also reported that in most studies, sensitivity and specificity findings for detecting clinical depression were above 80%. Thurber et al. (2002) provide further support that the ZSDS demonstrates incremental validity and discriminant validity relative to the MMPI-2 D scale, and their findings support the clinical utility for the use of 60 as a cutoff score by clinicians. The ZSDS has also been shown to adequately reflect change in treatment outcomes from psychotherapy or medications (Lambert et al. 1986), and to distinguish between clinicians’ global rating levels of depression (Biggs et al. 1978). Zung et al. (1965) reported discriminant validity for the instrument, obtaining significantly more elevated scores in depressed patients compared to patients with personality disorders, anxiety reactions, and adjustment reactions.

Clinical Uses

With its brief format, the ZSDS can be a helpful self-report measure when included in an assessment of depressive symptoms. In a neuropsychological evaluation, the ZSDS can yield important information about the psychological state of the individual, which may be having an effect on or underlie neurocognitive dysfunction. Research has supported its utility for assessing depressive symptoms in patients with a broad range of medical conditions including common neurological disorders such as Parkinson’s disease (Schrag et al. 2007), cerebrovascular disease (Curry et al. 2005), mild Alzheimer’s disease (Gottlieb et al. 1988), traumatic brain injury (Reza et al. 2007), and stroke (Meruna and Pinal 2012). The scale has been used to assess for depressive symptomatology of patients upon learning of their diagnosis with Alzheimer’s disease (Mormont et al. 2014). The ZSDS can also be used to aid in tracking functioning over time, assessing response to treatment, and examining physical recovery (e.g., Matsuzaki et al. 2015). A particularly significant advantage of the ZSDS is that it does not need to be purchased and can be easily accessed from many sources online including: http://healthnet.umassmed.edu/mhealth/ZungSelfRatedDepressionScale.pdf.

See Also