An interventional study of Clinical Hypnosis and Non-Hypnotic Guided Imagery in Dissociative Symptoms, sponsored by University of Rome Foro Italico. Not yet recruiting at 1 site in Italy. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-26.
Sponsored by University of Rome Foro Italico · Not applicable, Interventional, and Treatment
This randomized controlled trial aims to investigate whether a brief clinical hypnosis intervention can reduce dissociative symptoms more effectively than guided imagery in adults receiving psychiatric care.
Dissociative symptoms may include feelings of detachment from oneself or the surrounding environment, difficulties with memory, changes in the sense of identity, and a reduced sense of control over one's experiences. These symptoms can interfere with everyday functioning and occur across different mental health conditions.
The study will enroll approximately 160 adults with clinically significant dissociative symptoms. Participants will be randomly assigned to one of two groups: clinical hypnosis or non-hypnotic guided imagery. Both interventions will consist of four individual, in-person sessions lasting approximately 50 minutes each, delivered over 4-6 weeks alongside usual psychiatric care.
The clinical hypnosis intervention is designed to help participants recognize changes in their mental and bodily experiences, maintain awareness during these changes, and practice intentionally regulating them. The guided imagery intervention focuses on relaxation, sensory awareness, grounding, and emotional stabilization without using hypnosis-specific techniques.
The main outcome will be the severity of dissociative symptoms, measured using the Dissociative Experiences Scale-II (DES-II) approximately one week after the final session. Additional assessments will examine quality of life, psychological symptoms, and the safety and tolerability of both interventions. Follow-up evaluations at 3 and 6 months will assess whether any changes in dissociative symptoms are maintained.
The study will also explore whether participants' sense of control over their experiences may help explain treatment-related changes in dissociative symptoms.
**Scientific Background and Rationale**
Clinically significant dissociation involves disruptions in the integration of consciousness, memory, identity, perception, and the perceived control over mental states and behavior. Dissociative symptoms occur across a range of psychiatric conditions and are associated with considerable psychological distress and functional impairment. Despite their clinical relevance, evidence supporting specific psychological interventions targeting dissociative symptoms remains limited, particularly from adequately controlled randomized trials.
Clinical hypnosis is of particular interest because hypnosis and dissociation share certain phenomenological characteristics, including absorption, alterations in self-experience, and changes in perceived agency. However, these phenomena are conceptually distinct, and their relationship does not necessarily imply a shared underlying mechanism.
The HYDRA trial is informed by the clinical hypothesis that some spontaneous dissociative experiences may be understood as dysregulated self-hypnotic processes. This hypothesis is used as a therapeutic framework rather than an established explanation of dissociation. Accordingly, the intervention investigates whether structured practice in intentionally regulating hypnotic and absorption-like experiences may help individuals develop greater awareness of and control over experiences that are ordinarily perceived as involuntary.
**Conceptual Framework: Volitional Hypnosis**
For the purposes of this study, *volitional hypnosis* is defined as a study-specific operational construct referring to the capacity to intentionally initiate, observe, modulate, and terminate hypnotic or absorption-like experiential states while maintaining reflective awareness.
The clinical hypnosis intervention is informed by Ericksonian principles of individualized therapeutic communication, utilization, indirect suggestion, metaphor, and experiential learning. Within a structured and manualized framework, participants progressively practice recognizing early changes in experiential states, maintaining reflective awareness during these changes, and deliberately returning to a grounded, present-oriented state.
The intervention is conceived as an adjunctive self-regulation and skill-acquisition module rather than a comprehensive psychotherapy. It does not require the retrieval or processing of traumatic memories, and procedures intended to recover allegedly inaccessible memories are excluded.
**Rationale for the Active Comparator**
Non-hypnotic guided imagery was selected as an active comparator to provide a credible stabilization-oriented intervention while controlling for several nonspecific therapeutic factors, including therapist attention, treatment expectancy, focused attention, relaxation, mental imagery, and grounding.
The comparator incorporates structured imaginative and attentional exercises but excludes formal hypnotic induction, trance-deepening procedures, and suggestions explicitly aimed at intentionally entering, modifying, or terminating hypnotic states.
Because guided imagery may itself support emotional regulation and experiential engagement, it is not considered an inert control condition. This comparison is intended to provide a rigorous test of whether the explicit hypnotic framework and systematic training of volitional state regulation offer additional therapeutic benefits beyond those associated with a credible non-hypnotic psychological intervention.
**Hypothesized Processes of Change**
The primary clinical hypothesis is that clinical hypnosis will produce greater reductions in dissociative symptom severity than guided imagery.
An additional exploratory hypothesis concerns sense of agency, defined as the subjective experience of control over one's actions and experiences. The study will investigate whether changes in sense of agency during treatment are associated with subsequent changes in dissociative symptoms.
Baseline individual differences in hypnotic suggestibility, interoceptive awareness, and alexithymia will also be explored as potential moderators or prognostic factors of treatment response. These analyses are exploratory and are not intended to establish causal mechanisms.
**Safety and Clinical Considerations**
Given the potential vulnerability of individuals experiencing clinically significant dissociation, both interventions incorporate standardized procedures for monitoring distress, dissociative destabilization, orientation, and perceived control. Procedures for grounding, reorientation, temporary suspension, and clinical reassessment are prespecified and applied consistently across treatment conditions.
Adverse events and treatment tolerability will be systematically monitored. Independent clinical safety oversight is planned throughout the study.
By comparing clinical hypnosis with an active psychological intervention, the HYDRA trial aims to clarify the potential clinical utility, safety, and specific contribution of volitional hypnotic training in the management of dissociative symptoms.
41 studies on the registry are indexed under Dissociative Disorders; 13 are open to participants now.
This study's planned enrollment of 160 is above the median of 50 across 34 interventional studies indexed under Dissociative Disorders.
Browse Dissociative Disorders studies →University of Rome Foro Italico is the lead sponsor of 4 studies on the registry; 2 are open to participants now.
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Inclusion Criteria: Age 18 years or older.
Exclusion Criteria:
Concurrent participation in another structured experimental intervention specifically targeting dissociative symptoms.
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Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
DSM diagnostic criteria
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants assigned to this arm will receive four individual, in-person sessions of manualized Ericksonian clinical hypnosis, delivered approximately every 10-12 days. Each session will last approximately 50 minutes (±5 minutes). The intervention is designed to develop the ability to recognize, observe, and intentionally regulate dissociative or absorption-like experiential states while maintaining reflective awareness. Treatment progressively focuses on stabilization and recognition of experiential changes, dual awareness, voluntary modulation of hypnotic states, and consolidation of self-regulation skills. Sessions incorporate permissive hypnotic induction, individualized therapeutic metaphors, indirect suggestions, structured experiential exercises, and standardized grounding and reorientation procedures. The intervention does not involve trauma-memory retrieval or processing. Clinical hypnosis will be delivered as an adjunct to usual psychiatric care, which participants will
Behavioral: Clinical Hypnosis
Participants allocated to this arm will receive four individual, in-person sessions of manualized non-hypnotic guided imagery, delivered approximately every 10-12 days. Each session will last 50 minutes (±5 minutes), matching the experimental condition in duration, frequency, and therapist contact. The intervention focuses on sensory grounding, voluntary mental imagery, attentional flexibility, and emotional stabilization. Participants will progressively practice constructing calming mental images, maintaining awareness of their physical surroundings, shifting attention between imagined and external sensory experiences, and independently applying these strategies in daily life. The intervention will exclude formal hypnotic induction, trance-deepening procedures, post-hypnotic suggestions, and techniques explicitly aimed at intentionally entering, modifying, or terminating hypnotic states. Participants will continue to receive their usual psychiatric care throughout the trial.
Behavioral: Non-Hypnotic Guided Imagery
A manualized, four-session Ericksonian clinical hypnosis intervention designed to develop intentional regulation of dissociative and absorption-like experiences. Sessions incorporate permissive hypnotic induction, therapeutic metaphors, indirect suggestions, dual-awareness training, and structured practice in recognizing, modulating, and terminating hypnotic states. Each individual session lasts approximately 50 minutes and is delivered in person every 10-12 days. The intervention is provided alongside usual psychiatric care.
Also known as: Volitional Hypnosis
A manualized, four-session non-hypnotic guided imagery intervention focusing on sensory grounding, voluntary mental imagery, attentional flexibility, and emotional stabilization. Sessions involve structured imagery exercises, present-moment sensory awareness, and attention-shifting practices, without formal hypnotic induction or trance-deepening procedures. Each individual session lasts approximately 50 minutes and is delivered in person every 10-12 days. The intervention is provided alongside usual psychiatric care.
Dissociative Symptom Severity (DES-II Total Score) Copia
Dissociative symptom severity will be assessed using the Dissociative Experiences Scale-II (DES-II), a 28-item self-report questionnaire measuring the frequency of dissociative experiences. The total score is calculated as the mean of the 28 item scores and ranges from 0 to 100, with higher scores indicating greater dissociative symptom severity. The primary endpoint is the DES-II total score at post-treatment. The primary treatment effect will be estimated as the adjusted between-group difference in post-treatment DES-II scores, controlling for baseline DES-II.
Time frame: 7 ± 3 days after the fourth intervention session (post-treatment).
Dissociative Symptom Severity at 3-Month Follow-up (DES-II)
Dissociative symptom severity will be assessed using the Dissociative Experiences Scale-II (DES-II), a 28-item self-report measure. The total score ranges from 0 to 100, with higher scores indicating greater dissociative symptom severity. This secondary endpoint will evaluate maintenance of treatment effects at 3-month follow-up.
Time frame: 3 months after Session 4 (±14 days)
Dissociative Symptom Severity at 6-Month Follow-up (DES-II)
Dissociative symptom severity will be assessed using the Dissociative Experiences Scale-II (DES-II), a 28-item self-report measure. The total score ranges from 0 to 100, with higher scores indicating greater dissociative symptom severity. This secondary endpoint will evaluate maintenance of treatment effects at 6-month follow-up.
Time frame: 6 months after Session 4 (±14 days).
Global Psychological Distress (SCL-90-R Global Severity Index)
Global psychological distress will be assessed using the Global Severity Index (GSI) of the Symptom Checklist-90-Revised (SCL-90-R). The GSI summarizes overall psychological symptom distress, with higher scores indicating greater severity. Post-treatment scores will be compared between groups, adjusting for baseline values.
Time frame: Baseline and 7 ± 3 days after Session 4 (post-treatment).
PTSD Symptom Severity (CAPS-5 Total Score)
PTSD symptom severity will be assessed using the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5), restricted to participants meeting DSM-5 Criterion A for traumatic exposure at baseline. The total symptom severity score is calculated by summing the severity ratings of the 20 DSM-5 PTSD symptoms, ranging from 0 to 80, with higher scores indicating greater symptom severity. The same index traumatic event will be used at baseline and post-treatment.
Time frame: Baseline and 7 ± 3 days after Session 4 (post-treatment).
Anxiety Symptom Severity (GAD-7 Total Score)
Anxiety symptom severity will be assessed using the Generalized Anxiety Disorder-7 (GAD-7), a seven-item self-report questionnaire measuring symptoms over the preceding two weeks. Total scores range from 0 to 21, with higher scores indicating greater anxiety severity. Post-treatment scores will be compared between groups, adjusting for baseline values.
Time frame: Baseline and 7 ± 3 days after Session 4 (post-treatment).
Depressive Symptom Severity (PHQ-9 Total Score)
Depressive symptom severity will be assessed using the Patient Health Questionnaire-9 (PHQ-9), a nine-item self-report questionnaire measuring depressive symptoms over the preceding two weeks. Total scores range from 0 to 27, with higher scores indicating greater depressive symptom severity. Post-treatment scores will be compared between groups, adjusting for baseline values.
Time frame: Baseline and 7 ± 3 days after Session 4 (post-treatment).
Quality of Life (WHOQOL-BREF)
Quality of life will be assessed using the World Health Organization Quality of Life-BREF (WHOQOL-BREF), a 26-item self-report questionnaire evaluating four domains: physical health, psychological health, social relationships, and environment. Domain scores will be calculated according to standard WHO scoring procedures, with higher scores indicating better quality of life. The four domain scores will be analyzed separately, without calculating an overall total score. Post-treatment scores will be compared between treatment groups, adjusting for the corresponding baseline values.
Time frame: Baseline and 7 ± 3 days after Session 4 (post-treatment).
Sense of Agency (SoAS) - Exploratory Process Measure
Sense of agency will be assessed using the Italian version of the Sense of Agency Scale (SoAS). The scale measures individuals' subjective experience of control over their actions and experiences. Sense of agency is a prespecified exploratory process measure. The study will examine whether differences in sense of agency between treatment groups at the intermediate assessment, adjusted for baseline SoAS, are associated with subsequent differences in dissociative symptom severity at post-treatment. Exploratory mediation analyses will investigate this potential relationship without assuming that a causal mechanism has been established.
Time frame: Baseline; after Session 2 and before Session 3; and 7 ± 3 days after Session 4 (post-treatment).
Plan to share: Undecided — Individual participant data (IPD) will not be made openly available due to the clinical sensitivity of the study population and the potential risk of participant re-identification. De-identified and data-minimized participant-level datasets may be shared with qualified researchers upon reasonable request, subject to participant consent, Ethics Committee approval, applicable GDPR requirements, and an appropriate data-use agreement. Data elements presenting an unacceptable risk of re-identification will not be shared.
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University of Rome Foro Italico