How do you interpret the Cambridge Depersonalization Scale (CDS)?

Interpreting the Cambridge Depersonalization Scale (CDS)

The Cambridge Depersonalization Scale (CDS) is a validated self-rating questionnaire designed to measure the frequency and duration of depersonalization symptoms over a 6-month period, with higher scores indicating more severe depersonalization symptoms.

Overview of the CDS

The CDS was developed based on a comprehensive study of depersonalization phenomenology and has demonstrated strong psychometric properties:

• Original version contains multiple items capturing the frequency and duration of depersonalization symptoms 1
• High internal consistency (Cronbach's alpha = 0.89) and reliability (split-half reliability = 0.92) 1
• Shows specific correlations with the depersonalization subscale of the Dissociation Experiences Scale (r=0.80) 1

Scoring and Interpretation

Full CDS Version

The original CDS effectively differentiates patients with DSM-IV depersonalization disorder from other clinical groups, including those with anxiety disorders and temporal lobe epilepsy 1. When interpreting scores:

• Higher scores indicate more severe and frequent depersonalization experiences
• Consider both frequency and duration of symptoms (both dimensions are captured in the scale)
• Factor analysis reveals the CDS measures multiple dimensions of depersonalization including:
  • Inauthenticity
  • Self-Negation
  • Self-Objectification
  • Derealization
  • Body Detachment 2

CDS-2 (Short Version)

For screening purposes, the two-item version (CDS-2) can be used:

• Consists of two items from the original scale that best discriminate clinically significant depersonalization 3
• Using a cut-off score of ≥3 provides:
  • Sensitivity: 78.9%
  • Specificity: 85.7% 3
• Case-level depersonalization is found in approximately 3.4% of the general population using this threshold 4

Clinical Applications

When using the CDS in clinical practice:

1. Diagnostic Aid: Use as a supplementary tool alongside clinical interviews to identify depersonalization symptoms

2. Severity Assessment: Quantify symptom severity to guide treatment planning and monitor progress

3. Differential Diagnosis: While depersonalization is strongly associated with depression and anxiety, principal component analysis confirms it is a distinct psychopathological syndrome 4

4. Research Applications: The CDS has been used to identify neural correlates of depersonalization/derealization disorder through EEG analysis 5

Important Considerations

• The CDS measures symptoms over the past 6 months, so it reflects persistent rather than transient experiences
• Depersonalization symptoms often co-occur with anxiety and depression but represent a distinct syndrome 4
• When interpreting scores, consider the patient's overall clinical presentation and functional impairment
• The scale should be used as part of a comprehensive assessment rather than as a standalone diagnostic tool

Common Pitfalls to Avoid

1. Diagnostic Overshadowing: Avoid attributing depersonalization symptoms solely to comorbid conditions like anxiety or depression

2. Threshold Interpretation: Remember that subclinical depersonalization experiences are common in the general population (3.4% meet case-level criteria) 4

3. Cultural Considerations: Be aware that cultural concepts of distress may influence how depersonalization symptoms are experienced and reported 6

4. Developmental Factors: When assessing younger populations, consider developmental appropriateness of symptoms and use measures validated for that age group 6

By using the CDS appropriately, clinicians can better identify, quantify, and monitor depersonalization symptoms, leading to improved diagnosis and treatment planning for patients experiencing these distressing phenomena.