Augmentation of EMDR With tDCS in the Treatment of Fibromyalgia

Fibromyalgia (FM) affects 2-4% of the general population with typical symptoms such as generalized and widespread pain, sleep disturbances, problems in memory and attention, anxiety and depression. Pharmacological treatment and psychotherapeutic interventions have produced limited effects so far. Interestingly, lifetime psychosocial adversities are substantially elevated in FM but no interventions are currently offered. Given the complex etiology of FM, combining a psychotherapy with other treatment options can maximize the potential benefit of this intervention. The investigators will test in Barcelona, whether a trauma-oriented therapy, Eye Movement Desensitization Reprocessing (EMDR), in combination with a non-invasive brain stimulation technique, transcranial Direct Current Stimulation (tDCS), can improve typical FM symptoms. Outcomes Primary outcomes: 1. To test whether EMDR plus tDCS or EMDR plus sham-tDCS in comparison to TAU group, improve pain intensity, depressive and anxious symptoms and trauma associated symptoms after therapy and follow-up. 2. To test whether an improvement in pain intensity, depressive and anxious symptoms and trauma associated symptoms can be augmented by simultaneous tDCS comparing EMDR plus tDCS with EMDR plus sham-tDCS after the intervention and whether this is maintained at the follow-up visit. Secondary outcomes: 3. To test whether the EMDR plus tDCS or EMDR plus sham-tDCS in comparison to TAU group, improves more in subjective wellbeing after the treatment, and whether this is maintained at the follow-up visit. Indicators to monitor clinical changes will be performed via various standard self- and hetero-applied scales by blind-to-treatment raters and information provided by patients and the medical chart IT system of our catchment area at baseline (visit 1), post treatment at 6 months (visit 2), and follow-up evaluation at 12 months (visit 3). This multicenter collaborative project will involve the participation of the Psychiatric Department of the Parc de Salut Mar responsible for coordinating the study, the Rheumatology Department of the Parc de Salut Mar responsible for patient recruitment, and the Cognitive Neuro-Lab of the Universitat Oberta de Catalunya for guidance and council on tDCS use. Design Within a double-blind randomized controlled design, patients will be randomized to one of the following three treatment arms: EMDR with tDCS (20 sessions) vs EMDR with sham-tDCS (20 sessions) vs TAU. Psychotherapists, raters, and patients will be kept blind for tDCS treatment conditions until the end of the trial. Participants The patient sample will consist of 96 females fulfilling the 2016 American College of Rheumatology criteria for FM based on clinical interview (Wolfe et al, 2010). Interventions * EMDR therapy * transcranial Direct Current Stimulation (tDCS) * Treatment as Usual Randomizations Participants were randomly assigned to one of the three study groups using REDCap's stratified randomization module to ensure balanced allocation in terms of Revised Fibromyalgia Impact Questionnaire (FIQ-R) score and education level. When a new participant is enrolled, REDCap identifies their stratum based on the data for these two variables, then it assigns them to a study arm using block randomization within that stratum, favoring the arm with the fewest current assignments to maintain balance. The allocation sequence is concealed from outcome raters until participants have finished the trial. This randomization module enforces balance by prioritizing equal group sizes within strata, even with uneven stratum sizes, it provides real-time adaptations by adjusting assignments dynamically as participants enroll and it logs all randomization events for reproducibility purposes. Computation of sample size The main tests of the study will consist of assessing whether patients assigned to EMDR show different levels in the pain intensity variable using a standard formula for two-tailed t-tests. The total sample size required to detect large to very large effect size differences (Cohen's d ≥ 1) between three groups with a significance level of 0.05 and statistical power of 80% is 28. Assuming 15% dropouts, we will aim to randomize 96 patients, meaning 32 per group. Statistical Analysis The distribution of socio-demographic and clinical characteristics between groups at baseline will be summarized using descriptive statistics. The change in clinical and functional variables from the baseline evaluation to post intervention will be analyzed using linear model t-tests, including as regressors of no interest the potential confounders (age, pain score, anxiety and depression severity, and number of years in education). The statistical software used for the analysis will be the latest available version of R. The investigators will conduct an intention to treat (ITT) analysis, and will use the "Last Observation Carried Forward" (LOCF) method for losses at follow-up.