Acknowledgements: We would like to thank all patients and staff from Berkshire Healthcare Foundation Trust, Oxford Health NHS Foundation Trust and the Devon Partnership Trust who took part in this study.BACKGROUND: Intrusive mental imagery is associated with anxiety and mood instability within bipolar disorder and therefore represents a novel treatment target. Imagery Based Emotion Regulation (IBER) is a brief structured psychological intervention developed to enable people to use the skills required to regulate the emotional impact of these images. METHODS: Participants aged 18 and over with a diagnosis of bipolar disorder and at least a mild level of anxiety were randomly assigned (1:1) to receive IBER plus treatment as usual (IBER + TAU) or treatment as usual alone (TAU). IBER was delivered in up to 12 sessions overs 16 weeks. Clinical and health economic data were collected at baseline, end of treatment and 16-weeks follow-up. Objectives were to inform the recruitment process, timeline and sample size estimate for a definitive trial and to refine trial procedures. We also explored the impact on participant outcomes of anxiety, depression, mania, and mood stability at 16-weeks and 32-weeks follow-up. RESULTS: Fifty-seven (28: IBER + TAU, 27: TAU) participants from two sites were randomised, with 50 being recruited within the first 12 months. Forty-seven (82%) participants provided outcome data at 16 and 32-weeks follow-up. Thirty-five participants engaged in daily mood monitoring at the 32-week follow-up stage. Retention in IBER treatment was high with 27 (96%) attending ≥ 7 sessions. No study participants experienced a serious adverse event. DISCUSSION: The feasibility criteria of recruitment, outcome completion, and intervention retention were broadly achieved, indicating that imagery-focused interventions for bipolar disorder are worthy of further investigation
