Dose response and working memory limit in an eye movement desensitisation and reprocessing prospective case series

Background: Eye movement desensitization and reprocessing (EMDR) is a psychological therapy for post-traumatic stress disorder, or any disorder where the patient reports distressing imagery. We report here a prospective case series to test the prediction that the average number of distress images tends to seven. Methods: : Patients in a sexual health clinic were offered EMDR treatment. In total, 130 were entered and 50 completed treatment. All distressing images to all bad life events and anxieties reported were treated. Images that caused high distress or stopped progressing were usually decomposed until progress resumed. Results: : The median number of images per patient was seven. This required three treatment sessions in a total of five appointments, on average. This result was replicated twice in separate retrospective case series. Conclusion: We propose that EMDR works by unloading an overloaded memory buffer. If this bandwidth is liberated by treatment, this permits the cognitive and emotional change observed in EMDR treatment. The tendency to seven may signal involvement of the working memory limit. This approach enables clinical decision making and gives common ground with other psychotherapy methods.