Zung SDS: Self-Rating Depression Scale

The Zung SDS is a 20-item validated self-report measure of depression covering affective, somatic, psychomotor, and psychological symptoms. Scores expressed as an SDS Index (25–100). One of the most widely used depression scales in clinical research since 1965.

What is the Zung Self-Rating Depression Scale?

The Zung Self-Rating Depression Scale (SDS) was developed by William W. K. Zung at Duke University Medical Center in 1965, making it one of the earliest validated self-report measures of depression. Zung designed it to quantify depression based on a dimensional model, covering affective, physiological, psychomotor, and psychological symptoms across 20 items.

Each item is rated on a 4-point frequency scale (1–4). Ten items are negatively worded and scored directly; ten are positively worded and reverse-scored. The raw total (20–80) is converted to an SDS Index by multiplying by 100/80. An SDS Index of 50 or above indicates the presence of depression. The scale covers 20 characteristic signs and symptoms of depression, including sad affect, crying, sleep disturbance, appetite change, and hopelessness.

The Zung SDS is in the public domain and has been translated into over 30 languages. While the PHQ-9 is now more commonly used in primary care settings, the Zung SDS remains a reference standard in longitudinal research and is useful where a classic scale is required for comparison with historical data.

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Educational reference only. Cannot diagnose or replace clinical evaluation.

Zung SDS Interpretation

Zung (1965). SDS Index = (raw score / 80) × 100. Raw scores range from 20 to 80.

Track Depression Outcomes in HiBoop

Zung SDS alongside PHQ-9 and MADRS, longitudinal scoring to monitor treatment response across every patient.