Eye-movement desensitization and reprocessing: neurophysiological markers in the treatment of major depressive disorder

Major depressive disorder (MDD) is one of the most common psychiatric conditions, characterized by a complex aetiology including biological factors (e.g., brain structural, functional and hormonal abnormalities), physiological influences, and with psychological trauma serving as risk and maintenance factors. Although several different interventions, like psychotherapy and pharmacology, have been established and proved to be effective in the treatment for MDD, research is always seeking to improve already existing treatments and implement new ones. Eye-movement desensitization and reprocessing (EMDR) is an eight-phases structured psychotherapy treatment which aims at treating individuals who have experienced distressing and traumatic events. Originally developed and tested for post-traumatic stress disorder (PTSD), EMDR has emerged as a promising integrative treatment for several other psychiatric conditions, including MDD, with the aims to decrease symptoms and negative affect, as well as enhance recovery and the development of coping skills, while preventing relapse. Research results suggest that EMDR could contribute to significantly reduce depressive symptoms, with effects comparable to other standard treatments. Recent findings advocate distinct neurobiological patterns of brain activation associated with a cognitive processing of traumatic events and decreased activity in the prefrontal limbic cortex. In addition, studies concerning physiological markers found patterns of autonomic activity reflecting psychophysiological de-arousal, as shown by increasing heart rate variability. However, further research and randomized controlled trials need to be carried out as current literature is not fulfilling yet, due to the limited number of studies and various methodological issues, such as small sample size, high risk of bias and heterogeneity.