Zung Self-Rating Depression Scale (SDS)

Have you been feeling down for a while now?

Depression is more than just feeling sad. It affects how you think, feel, and function. Core symptoms include persistent sadness, loss of interest in things you once enjoyed (anhedonia), and low energy.

About the SDS

The Self-Rating Depression Scale (SDS) was developed by William W. K. Zung in 1965. It uses 20 items to assess depressive symptoms across four domains:

• Affective domain: mood, crying spells
• Somatic domain: sleep, appetite, fatigue
• Psychological domain: confusion, hopelessness, irritability
• Behavioral domain: diminished activity, loss of interest

Unlike the CES-D (for epidemiological screening) and PHQ-9 (aligned with DSM-5), the SDS uniquely assesses both the intensity and frequency of depressive symptoms. Its mixed design of 12 positively-worded and 8 reverse-scored items reduces response bias.

Scoring

Each item is rated 1-4 (1=a little of the time, 4=most of the time). 10 items are reverse-scored. Raw score range: 20-80. Standard index = raw score x 1.25 (range 25-100).

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Raw Score	Index	Level
<=39	<50	Normal range
40-47	50-59	Mild depression
48-55	60-69	Moderate depression
>=56	>=70	Severe depression

Notes

• Internal consistency: alpha = 0.82-0.92; convergent validity with Hamilton Rating Scale: r = 0.60-0.80
• This is a screening tool, not a diagnostic instrument
• If your score is elevated or you have concerns, please speak with a qualified mental health professional