📈 Does EMDR Work?
How much does EMDR actually help? Researchers measure this with effect sizes.
An effect size quantifies how much a treatment moves the needle compared to no treatment or a control condition. Cohen’s conventions: 0.2 = small, 0.5 = medium, 0.8 = large. Most effective psychological treatments sit between 0.5–1.0 compared to control conditions.
EMDR’s Effect Sizes
Meta-analyses consistently place EMDR’s effect sizes in the large range for PTSD outcomes. Compared to waitlist controls, effect sizes typically fall between 1.0 and 1.5. Compared to active treatment comparators (other bona fide therapies), effects are smaller but still clinically meaningful — roughly equivalent to the best alternative treatments.
To contextualise: antidepressant medications for depression typically show effect sizes of approximately 0.3 versus placebo. EMDR’s effect sizes for PTSD are substantially larger.
Speed Advantage
Beyond magnitude, EMDR demonstrates a speed advantage in several head-to-head comparisons with CBT-based approaches. Similar outcomes are achieved in fewer sessions. This has significant implications for access and cost.
Honest Limits
Effect sizes are averages. They tell you nothing about whether EMDR will work for a specific individual. Roughly 20–27% of people do not complete trauma-focused treatment, and among those who complete, a meaningful minority retain residual symptoms. EMDR is highly effective — it is not universally effective.
Key meta-analyses
Bisson et al. (2013) Cochrane review found EMDR superior to waitlist and comparable to trauma-focused CBT. Chen et al. (2014) meta-analysis: large effect sizes for PTSD, maintained at follow-up. Cusack et al. (2016) Agency for Healthcare Research and Quality systematic review confirmed EMDR as among the most effective treatments available. Bradley et al. (2005) provides the dropout and non-response data cited above.