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What is the International Dissociative Disorders Questionnaire?
The International Dissociative Disorders Questionnaire (IDDQ) is a new screening instrument currently being developed for the assessment of dissociative disorders according to the ICD-11.
Its purpose is to help clinicians and researchers identify clinically relevant dissociative symptoms in a structured, concise, and diagnostically meaningful way. The IDDQ is intended to cover the full range of disorders included in the ICD-11 chapter on dissociative disorders, rather than assessing dissociation only as a single general construct.
The questionnaire is being designed as a screening and diagnostically oriented assessment tool. It should help indicate whether a more detailed clinical evaluation of one or more dissociative disorders may be warranted. It is not intended to replace a comprehensive clinical interview, differential diagnosis, or professional judgement.
Why is the IDDQ needed?
Many existing dissociation questionnaires were developed before the introduction of the ICD-11 or are based on different diagnostic frameworks. Some assess dissociative experiences broadly, but do not systematically screen for the individual disorders included in the ICD-11 chapter on dissociative disorders.
The IDDQ is intended as a screening questionnaire covering the full range of ICD-11 dissociative disorders. It is designed to support the early recognition of clinically relevant symptoms and to indicate when a more comprehensive diagnostic assessment may be warranted. It is not intended to replace a clinical interview or establish a diagnosis on its own.
Purpose of the IDDQ
The main objectives of the IDDQ are to:
support the early recognition of dissociative disorders
provide a structured overview of clinically relevant dissociative symptoms
distinguish between different ICD-11 dissociative disorder profiles
guide further diagnostic assessment
improve consistency in clinical and research settings
facilitate internationally comparable research
The instrument is intended for use in mental health services, specialist trauma and dissociation settings, general psychiatric and psychotherapeutic care, and clinical research.
Who is the IDDQ for?
The IDDQ is primarily being developed for use by:
psychiatrists
psychologists and psychotherapists
physicians and other qualified healthcare professionals
researchers working on dissociation, trauma, and related conditions
clinical services conducting structured intake or diagnostic assessments
The final questionnaire may be completed as a self-report measure, but its results should always be interpreted within the broader clinical context. Elevated scores or positive screening results should lead to further assessment rather than being treated as a diagnosis.
ICD-11 orientation and disorders covered
The theoretical and diagnostic framework of the IDDQ is based on the ICD-11 classification of dissociative disorders.
ICD-11 defines dissociative disorders as involving involuntary disruption or discontinuity in the integration of psychological and physiological functions. These disturbances may affect identity, sensations, perceptions, emotions, thoughts, memories, control over bodily movements, and behaviour. They may be partial or complete and can vary over time.
The IDDQ aims to translate these broad diagnostic concepts into concrete, clearly formulated questions that can be used in clinical practice and research.
The IDDQ is intended to screen for the core features of the dissociative disorders included in ICD-11, including:
Dissociative neurological symptom disorder
6B60
Dissociative amnesia
6B61
Trance disorder
6B62
Possession trance disorder
6B63
Dissociative identity disorder
6B64
Partial dissociative identity disorder
6B65
Depersonalisation-derealisation disorder
6B66
The final structure will depend on the results of the Delphi study and subsequent psychometric validation.
Conceptual relationship to the ITQ
The development of the IDDQ is conceptually informed by the logic of the International Trauma Questionnaire (ITQ).
Like the ITQ, the IDDQ is intended to focus on the essential features of ICD-11 disorders, use clear and accessible language, and apply transparent scoring principles. The aim is not to measure every possible dissociative experience, but to identify the most clinically informative symptoms associated with specific ICD-11 diagnoses.
This approach reflects the ICD-11 emphasis on clinical utility, diagnostic clarity, and international applicability.
Languages and future availability
The IDDQ is being developed as an international instrument. A central aim is to ensure that the final questions are understandable, clinically relevant, and culturally appropriate across different languages and healthcare systems.
The first research version is being developed in English. Additional language versions are planned as part of the international collaboration. Only formally translated and validated versions should ultimately be used for clinical or research purposes.
The IDDQ is currently under development and is not yet available as a validated clinical instrument. Until the development process is completed, the current item pool should be regarded as a research version only and should not be used as a stand-alone diagnostic instrument.
Follow the development on our Research page or contribute your expertise.