Targeting dissociation using cognitive behavioural therapy in voice hearers with psychosis and a history of interpersonal trauma : A case series

Objectives: Previous studies have suggested that dissociation might represent an important mechanism in the maintenance of auditory verbal hallucinations (i.e., voices) in people who have a history of traumatic life experiences. This study investigated whether a cognitive behavioural therapy (CBT) intervention for psychosis augmented with techniques specifically targeting dissociative symptoms could improve both dissociation and auditory hallucination severity in a sample of voice hearers with psychosis and a history of interpersonal trauma (e.g., exposure to sexual, physical, and/or emotional abuse). Design: Case series. Methods: A total of 19 service users with psychosis were offered up to 24 therapy sessions over a 6-month intervention window. Participants were assessed four times over a 12-month period using measures of dissociation, psychotic symptoms severity, and additional secondary mental-health and recovery measures. Results: Sixteen participants engaged in the intervention and were included in last-observation-carried-forward analyses. Dropout rates were in line with those of other CBT for psychosis trials (26.3%). Repeated measures ANOVAs revealed large and significant improvements in dissociation (drm = 1.23) and hallucination severity (drm = 1.09) by the end of treatment; treatment gains were maintained 6 months following the end of therapy. Large and statistically significant gains were also observed on measures of post-traumatic symptoms, delusion severity, emotional distress, and perceived recovery from psychosis. Conclusions: The findings of this case series suggest that the reduction of dissociation represents a valuable and acceptable treatment target for clients with auditory verbal hallucinations and a trauma history. Future clinical trials might benefit from considering targeting dissociative experiences as part of psychological interventions for distressing voices. Practitioner points: Practitioners should consider the role of dissociation when assessing and formulating the difficulties of voice hearers with a history of trauma. Techniques to reduce dissociation can be feasibly integrated within psychological interventions for voices. Voice hearers with histories of trauma can benefit from psychological interventions aimed at reducing dissociation.