A randomised controlled trial evaluating the efficacy and mechanisms of eye movement desensitisation and reprocessing therapy (EMDR) compared with treatment as usual for adults with depression in primary care

Background: Depression is a common condition in primary care and a leading cause of disability and lost work days. Only half of patients respond to the most common treatments (antidepressants and cognitive behavioural therapy (CBT)). EMDR is a NICE-recommended trauma-focused intervention for post-traumatic stress disorder (PTSD). The protocol has been adapted for depression. It emphasises the importance of reprocessing dysfunctionally stored memories that may arise after stressful life events (e.g. job loss) or traumatic experiences (e.g. childhood abuse) and which may predispose to and maintain depression. Targeting memories linked to depression using EMDR provides a new avenue for treatment that may act via different mechanisms. There is some evidence that EMDR may reduce depressive symptoms. However, there is no robust evidence of efficacy, and it is unclear how EMDR works. Aims & Objectives: To establish the efficacy of EMDR (in addition to usual GP care (UC)) compared with UC for patients with depression in primary care. The embedded mechanistic study will determine whether reductions in depression are mediated by key memory-processing mechanisms and if working memory capacity is associated with treatment response. A nested qualitative study will examine the acceptability of EMDR for depression, further explore mechanisms, and identify possible causes of differing responses. An intervention costing exercise will estimate the cost of delivering EMDR in the NHS. Methods: Two parallel group multi-centre individually randomised controlled trial with allocation at the level of the individual set in primary care. Eligible patients aged =18 years, have a Beck Depression Inventory (BDI-II) score =14 and meet ICD-11 depression criteria. Participants will be randomised to the intervention (12-18 sessions of EMDR: weekly 60-90 mins individual in-person) in addition to UC or to continue with UC. The primary (efficacy) outcome will be the score on the BDI-II at 26 weeks. Secondary outcomes will include remission (BDI-II score<10), anxiety, function, quality of life and outcomes at 52 weeks. Mediators will be measured during treatment at 16 weeks. A sample size of 380 participants will provide 90% power at 2-sided 5% significance level to detect an effect size of 0.378 allowing for 25% attrition at 26 weeks. With this sample size we will have 87.2%, 87% and 79.4% power to detect an indirect effect of 40%, 30% and 20%. Interviews with participants will take place following completion of their primary (efficacy) outcomes (20 intervention, 10 UC) and with all trial therapists and supervisors. Interviews will be audio-recorded, transcribed verbatim and analysed thematically. Data on EMDR delivery and supervision will be collected and associated costs estimated using nationally available sources for unit costs. Timelines for delivery: Start: 1st March 2025. Set-up, approvals and therapist training: 8 months. 6-month internal pilot. If ‘go’ criteria met, recruit to 31 Oct 2027 and follow-up to 31 Oct 2028. 6 months for data analysis and reporting writing. Final report: 30 April 2029. Anticipated impact and dissemination: We will develop a plan with our collaborators, stakeholders and PPI representatives to ensure outputs are widely disseminated. The results will influence NICE guidelines and plans for increasing the number of accredited EMDR therapists in NHS talking therapy services.