Zung Self-Rating Depression Scale

The Self-Rating Depression Scale (SDS), developed by Professor Zung at Duke University School of Medicine in 1965, is one of the most widely used depression screening tools. Its 20 items cover emotional, physical, and psychological symptoms. It is used for rapid screening, severity assessment, treatment monitoring, and epidemiological surveys. Its simplicity and short completion time, about 5 minutes, have led to widespread use in clinical care, counseling, and research.

The SDS uses a 4-point scale (1–4) covering the past week. Multiply the raw total (20–80) by 1.25 to obtain a standardized score (25–100). Interpretation: <53 = normal range, 53–62 = mild depression, 63–72 = moderate depression, and ≥73 = severe depression. Ten items, including feeling best in the morning, are reverse-scored: 1 becomes 4, 2 becomes 3, 3 becomes 2, and 4 becomes 1. A standardized score ≥53 suggests possible depressive symptoms and a need for further professional assessment.

The SDS is intended for adults aged 18 and over with at least a junior secondary education. It suits community screening, initial counseling assessment, symptom monitoring in people with depression, and research. It is unsuitable for people with severe cognitive impairment, those unable to understand the items because of limited education, or those experiencing an acute psychotic episode. For older adults, a dedicated measure such as the GDS-15 is recommended.

The SDS and BDI are both commonly used measures of depressive symptoms. The SDS was developed by Zung and is based on symptom descriptions; the BDI was developed by Beck and draws on his cognitive theory. The SDS has 20 items. The full BDI has 21, while this site's BDI is a 13-item short form. SDS responses use a 1–4 scale; BDI items offer four statements scored 0–3. The SDS is often used for rapid screening and epidemiological surveys, while the BDI places more emphasis on cognitive symptoms and is widely used in clinical assessment. Both have evidence of reliability and validity. Choose the measure and version that fit your purpose, and remember that a questionnaire score alone cannot establish a diagnosis.

Ten of the 20 SDS items—2, 5, 6, 11, 12, 14, 16, 17, 18, and 20—describe positive states, such as feeling hopeful about the future. Selecting none or little of the time, normally scored 1, therefore indicates greater depression. These scores are reversed: 1 becomes 4, 2 becomes 3, 3 becomes 2, and 4 becomes 1. Reverse-keyed items discourage mechanical responses, improve reliability and validity, and support a fuller symptom assessment. The system reverses these scores automatically when calculating the total.

If your SDS standardized score is ≥53, consult a mental health professional. Pay particular attention to a score ≥63 (moderate depression), a high score on item 19 about others being better off if you were dead, symptoms lasting more than 2 weeks and seriously disrupting work or daily life, marked sleep or appetite changes or weight loss, and recurrence of a previous depressive episode. Even within the normal score range, persistent low mood and distress warrant support. The SDS is a screening tool, not a substitute for diagnosis, which requires a comprehensive assessment by a psychiatrist or psychotherapist.