Cambridge Depersonalisation Scale (CDS)
Also known as: CDS
The CDS is a 29-item self-report measure of depersonalisation and derealisation experiences, developed by Sierra and Berrios in 2000. It is the most widely used instrument for assessing dissociative symptom severity in both clinical and research settings, valuable for identifying depersonalisation disorder, monitoring treatment response, and understanding the prevalence of depersonalisation in anxiety, mood, and trauma populations.
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When to use it
Primary use: diagnostic assessment for depersonalisation disorder and measurement of depersonalisation/derealisation severity across psychiatric conditions. Screening for dissociative symptoms in panic disorder, PTSD, trauma, anxiety, depression, and early psychosis populations. Baseline and outcome measurement in treatment studies targeting dissociation. Not primary screening tool for dissociative identity disorder (which requires structured interview and systematic symptom assessment). Useful when patients report feeling unreal, detached, or observing themselves from outside.
Strengths & limitations
- Gold standard for depersonalisation measurement: most cited and validated instrument for quantifying depersonalisation/derealisation in research and clinical practice
- Frequency-duration scoring captures severity: captures both symptom frequency and duration, sensitive to time-course changes during treatment
- Discriminative validity: distinguishes depersonalisation disorder from anxiety, depression, and psychosis; strong diagnostic accuracy
- Multidimensional assessment: separate depersonalisation and derealisation subscales capture distinct dissociative phenomena with potentially different etiologies
- Transdiagnostic utility: depersonalisation occurs across anxiety, mood, trauma, and psychotic disorders; CDS measures transdiagnostic symptom cutting across diagnoses
- Frequency-duration complexity: dual-rating system increases completion time (15–20 min) and potential for error; more complex than single-rating instruments
- Limited psychometric data in some populations: most validation in European samples; limited data in Asian, African populations; cutoff scores may vary by culture/ethnicity
- Scoring interpretation not standardized: different research groups use different subscale combinations and cutoff scores; inconsistency limits comparison across studies
- Medical exclusion unclear: depersonalisation can result from medical conditions (partial seizures, vestibular disease, migraine, hypothyroidism); CDS cannot distinguish primary psychiatric from secondary depersonalisation
- Not diagnostic alone: CDS elevations indicate dissociation but do not specify etiology; comprehensive medical and psychiatric evaluation required
Frequently asked
What is the difference between depersonalisation and derealisation?
Depersonalisation involves feeling detached from one's body, mind, or self (e.g., observing oneself from outside, feeling like a robot, being in a dream within the body). Derealisation involves perceiving the external world as unreal, dreamlike, or distant (e.g., people appearing like robots, surroundings looking flat or two-dimensional, colors appearing faded). Both are dissociative; depersonalisation = detachment from self, derealisation = detachment from world. CDS measures both separately.
Is a CDS score of 70 diagnostic for depersonalisation disorder?
No. A CDS score ≥70 indicates significant depersonalisation/derealisation and warrants diagnostic evaluation, but does not constitute diagnosis alone. Depersonalisation disorder requires: (1) recurrent or persistent depersonalisation/derealisation; (2) reality testing remains intact during episodes; (3) significant distress or functional impairment; (4) symptoms not better explained by another disorder, substance use, or medical condition. CDS is component of diagnostic assessment, not sufficient alone.
What should I do if a patient scores >70 on the CDS?
Conduct comprehensive evaluation: (1) structured clinical interview assessing depersonalisation symptom history, duration since onset, triggers, and associated symptoms; (2) rule out medical causes (seizures, migraine, vestibular dysfunction, thyroid disease, hypoxia, substance use); (3) assess trauma history and current anxiety/depression severity; (4) clarify whether symptoms cause significant distress/impairment. High CDS occurs in panic disorder, PTSD, anxiety—not only depersonalisation disorder. Medical clearance is essential.
How does the frequency-duration scoring work and is it necessary?
Each item is scored: Frequency (0–3) × Duration (0–2) = item score (0–6). Frequency captures how often symptoms occur; Duration captures how long they last when they occur. A symptom occurring frequently but lasting only seconds is different from one occurring less frequently but lasting days. This dual-rating captures clinically meaningful severity variation. Some researchers use frequency alone; frequency × duration is more sensitive to change.
Is CDS available free for clinical use?
Yes. The CDS is freely available for research and clinical use in the public domain. It may be reproduced without copyright restriction. Scoring guidelines and norms appear in the original Sierra & Berrios (2000) publication and available through the authors. No licensing fees.
Sources
- Sierra, M., & Berrios, G. E. (2000). The Cambridge Depersonalisation Scale: a new instrument for the measurement of depersonalisation. Psychiatry Research, 93(2), 153–164. DOI: 10.1016/s0165-1781(00)00100-1 ↗
How to cite this page
ScholarGate. (2026, June 3). Cambridge Depersonalisation Scale (CDS). ScholarGate. https://scholargate.app/en/clinical-psychology/depersonalization-derealization-scale
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