Cognitive Behavior Therapy for Depersonalization-Derealization Disorder (CBT-f-DDD): a feasibility randomized trial

Abstract

Background: Depersonalization-derealization disorder (DDD) is characterized by feelings of “unreality” about the self and/or external world. Cognitive Behavioral Therapy adapted for DDD (CBT-f-DDD) has been effective in published clinical audits. This study aimed to provide feasibility and acceptability data. Methods: An individually randomized design of CBT-f-DDD versus Treatment as Usual (TAU) was carried out with adult DDD participants from NHS Trusts in London. The CBT-f-DDD group received individual sessions over a 6-month period from CBT therapists. Qualitative interviews were conducted with CBT-f-DDD participants and their clinicians. Eight feasibility objectives were evaluated (recruitment, retention, resources, representativeness, acceptability of study design and intervention, preliminary responses to intervention, and health economics). Results: Thirty participants with DDD were recruited over 13 months. Only 63% completed the final assessment, so retention needs improvement. Resources were acceptable. The sample was comparable to previous studies, although younger, with a shorter duration of DDD and lower mean DDD scores. In a post-study questionnaire, no aspect of the study or treatment was rated unacceptable; however, some areas need improvement. Qualitative interviews with participants and clinicians recorded positive responses to CBT-f-DDD. Those in the CBT arm had a mean decrease of 16.9 points (SD 43.6) on the Cambridge Depersonalization Scale versus a mean decrease of 5.5 points (SD = 25.0) for the TAU arm. Health economics analyses found that CBT-f-DDD saved £153 per person. Participants reported an additional 0.08 Quality-Adjusted Life Years at low cost. Conclusions: This study suggests that a subsequent RCT for CBT-f-DDD is feasible and represents the first step in the process of establishing evidence-based treatments for DDD. However, refinements to the current design and delivery were indicated for a future fully powered definitive RCT of CBT-f-DDD. Trial registration: ISRCTN, ISRCTN97686121. Retrospectively registered 5 January 2023: https://doi.org/10.1186/ISRCTN97686121.