A Systematic Narrative Review of EMDR therapy for Post-traumatic Stress Disorder

Definition and Origin: Eye-Movement Desensitization Reprocessing (EMDR) is an integrative psychotherapy developed by Shapiro (1995). It is described as a trans-diagnostic treatment used to address adverse life experiences, primarily Post-traumatic Stress Disorder (PTSD).
Theoretical Framework: EMDR therapy is based on the Adaptive Information Processing (AIP) model. This theory posits that psychopathology arises when memories of adverse life experiences are inadequately processed by the brain (Felitti et al., 1998).
Status and Recognition: EMDR is empirically validated and is recommended by the World Health Organization (2013) for the treatment of trauma. It is noted for its efficacy across different cultures and clinical populations.

Search 1: Meta-Analyses and Systematic Reviews:
- Scope: Evaluated all peer-reviewed meta-analyses and systematic reviews published prior to April 2017.
- Databases: ASSIA, CINAHL, Cochrane library, Medline, PsycArticles, PubMed, Science Direct Freedom Collection, and Web of Science.
- Criteria: Included English-language papers focusing on Randomized-Controlled Trials (RCTs) involving adults. Excluded non-peer-reviewed papers, pilot studies, and studies focusing solely on children or adolescents.
- Quality Assessment: Used the Critical Appraisal Skills Programme (CASP) tools. Only medium-to-high quality papers were included. Two meta-analyses (Chen et al., 2014 and Chen et al., 2015) were selected.
Search 2: Recent Randomized Controlled Trials (2014–2017):
- Scope: Identified individual RCTs published between January 2014 and April 2017 to update the findings of the 2014/2015 meta-analyses.
- Results: Four RCTs were included for review (Acarturk et al., 2016; Carletto et al., 2016; de Bont et al., 2016; ter Heide et al., 2016).

Chen et al. (2014):
- Sample: 26 RCTs featuring a total of $1,133$ participants from Taiwan.
- PTSD Symptoms: Reported a significant reduction in symptoms ( $p < 0.001$ ) with a moderate effect size (Hedge's $g = -0.662$ ).
- Comorbid Symptoms: Found significant reductions in depression ( $p < 0.001$ ; $g = -0.643$ ), anxiety ( $p < 0.001$ ; $g = -0.640$ ), and subjective distress ( $p < 0.01$ ; $g = -0.956$ ).
- Moderators: Efficacy was higher when therapy was delivered by experienced therapists ( $g = -0.753$ ) compared to inexperienced ones ( $g = -0.234$ ; $p = 0.007$ ). Longer sessions ( $> 60\,\text{min}$ ) were significantly more effective for depression and anxiety.
Chen et al. (2015):
- Sample: 11 RCTs with $424$ participants from China, comparing EMDR to Cognitive Behavioral Therapy (CBT).
- Comparison Findings: EMDR was significantly more effective than CBT in reducing PTSD symptoms ( $p = 0.05$ ).
- Sub-scale Specifics: EMDR outperformed CBT in reducing intrusion severity ( $p = 0.02$ ) and arousal ( $p = 0.04$ ). Treatment for avoidance symptoms showed no significant difference between EMDR and CBT ( $p = 0.1$ ).

Acarturk et al. (2016):
- Population: 70 Syrian refugees in Turkey.
- Findings: Participants in the waiting-list control group were $24.21$ times more likely to be diagnosed with PTSD compared to the EMDR group post-test. At 5-week follow-up, the risk remained $23$ times higher for the control group ( $p < 0.01$ ).
- Symptom Reduction: Significant improvement in avoidance, intrusion, and hyper-arousal ( $p < 0.01$ ).
Carletto et al. (2016):
- Population: 50 adults with multiple sclerosis in Italy.
- Findings: EMDR was significantly more effective than relaxation therapy ( $p = 0.049$ ). After $12$ to $15$ weeks, $17$ out of $20$ EMDR participants no longer met PTSD criteria. At 6-month follow-up, zero EMDR participants met the diagnosis.
de Bont et al. (2016):
- Population: 155 adults with chronic psychotic disorders in the Netherlands.
- Findings: EMDR significantly reduced paranoid thoughts post-treatment ( $p < 0.05$ ), though not at 6-month follow-up. Prolonged exposure was found to be significantly more effective than EMDR in reducing depression symptoms ( $p < 0.05$ ).
ter Heide et al. (2016):
- Population: 72 adult refugees in the Netherlands.
- Findings: Both EMDR and a stabilization control group showed significant improvement in trauma symptoms ( $p < 0.05$ ), but there was no significant difference in efficacy between the two interventions.

Psychosis and Social Functioning: In the de Bont et al. (2016) study, neither EMDR nor prolonged exposure significantly impacted auditory hallucinations or personal social performance compared to waiting lists.
Fatigue and Mood: Carletto et al. (2016) found that both EMDR and relaxation therapy significantly improved mood ( $p < 0.001$ ), fatigue severity ( $p = 0.029$ ), and functional assessment ( $p = 0.001$ ).
Quality of Life: ter Heide et al. (2016) found no significant differences in quality of life between EMDR participants and the stabilization control group.
Tolerability: All studies reported low dropout rates, suggesting EMDR is well-tolerated relative to other treatments like prolonged exposure.

Sample Sizes: Many RCTs were low-powered due to small sample sizes.
Homogeneity: Severe inconsistencies exist in study designs, outcome measures (19 different measures used across four RCTs), and versions of assessment scales.
Follow-up Data: Follow-up periods varied significantly (5 weeks to 6 months), with limited data available for long-term efficacy beyond $6\,\text{months}$ .
Economic Factors: None of the reviewed studies analyzed the cost-effectiveness of EMDR therapy compared to other treatments, despite claims in broader literature that EMDR may reduce healthcare costs through shorter treatment durations.

Practice Recommendations: EMDR therapy should be accessible to adults presenting with PTSD and comorbidities such as anxiety and depression. It can be delivered effectively across diverse cultural contexts.
Standardization: There is a critical need for standardized outcome measures to facilitate cross-study comparisons.
Research Needs:
- Larger RCT samples are required.
- Longitudinal evaluations extending beyond $6\,\text{months}$ .
- Comparative efficiency studies against other trauma-focused interventions (e.g., CBT).
- Specific research to compare adult PTSD treatment with child/adolescent treatment efficacy, as current evidence for younger populations is considered weak.