Research EMDR and Depression (meta analysis)
The Effectiveness of Eye Movement Desensitization and Reprocessing Toward Adults With Major Depressive Disorder: A Meta-Analysis of Randomized Controlled Trials
Shuya Yan1,2Yanyan Shan3Shuming Zhong1Haofei Miao2Yange Luo2Hanglin Ran2Yanbin Jia1*
1Department of Psychiatry, First Affiliated Hospital of Jinan University, Guangzhou, China
2School of Management, Jinan University, Guangzhou, China
3Psychology and Neuroscience Department, Duke University, Durham, NC, United States
The practice-based evidence suggests that it is possible to use eye movement desensitization and reprocessing (EMDR) to treat major depressive disorder (MDD), but its specific efficacy is unknown. A systematic search was carried out for randomized controlled trials comparing EMDR with a control condition group in MDD patients. Two meta-analyses were conducted, with symptom reduction as primary outcome and remission as exploratory outcome. Eight studies with 320 participants were included in this meta-analysis. The first meta-analysis showed that EMDR outperformed “No Intervention” in decreasing depressive symptoms (standardized mean difference [SMD] = −0.81, 95% CI = −1.22 to −0.39, p < 0.001, low certainty), but statistically significant differences were not observed in improving remission (risk ratio = 1.20, 95% CI = 0.87–1.66, p = 0.25, very low certainty). The second showed the superiority of EMDR over CBT in reducing depressive symptoms (mean difference [MD] = −7.33, 95% CI = −8.26 to −6.39, p < 0.001, low certainty), and improving remission (risk ratio = 1.95, 95% CI = 1.24–3.06, p = 0.004, very low certainty). Besides, anxiety symptoms and level of functioning could not be included as secondary outcome due to the lack of data. The present meta-analysis suggests that EMDR is more effective in treating MDD than “No Intervention” and CBT, particularly in individuals who have traumatic experience. However, this result should be considered with caution due to small sample size and low quality of trails.
Introduction
Major depressive disorder (MDD) is characterized by depressed mood, loss of interest, diminished ability to experience pleasure, and feelings of worthlessness or inappropriate guilt. According to the statistics released by the World Health Organization (WHO) in 2017, depression had affected more than 300 million people around the world, which means that 4.4% of the world's population is suffering from this disorder (1). In addition to emotional symptoms, MDD is also accompanied by a series of neurovegetative and cognitive symptoms (2). Given the severe impacts on quality of life and psychosocial functioning of affected people, MDD is deemed as the biggest contributor to global disability.
Psychological treatments have long been used to treat MDD. The latest clinical practice guideline of American Psychological Association (APA) recommends the use of cognitive-behavioral therapy (CBT) or interpersonal psychotherapy for the initial treatment of depression in adolescents. There was not enough evidence to recommend one psychotherapy treatment over another for adults and older adults with MDD, but in general, there was support for behavioral therapy; CBT and mindfulness-based cognitive therapy; and interpersonal psychotherapy. Among them, CBT is the most established evidence-based therapy. Multiple studies have found that CBT is effective in reducing depressive symptoms and preventing relapse when compared to usual care or placebo (3–5). For those with mild to moderate depressive symptoms, psychological intervention alone is proven effective (2). However, some patients still cannot fully benefit from them: after a full-session psychological therapy, only 53.7% participants can be evaluated as remission (6). There are various reasons why patients with MDD do not fully respond to psychotherapy. One of the reasons may be that the aforementioned interventions do not aim at particular clinical characterization of MDD patients, like early and/or recent environmental exposures (7). The distressing life experiences of MDD patients may not be effectively dealt with during interventions mentioned above, leading to unsatisfactory treatment outcomes.
Eye movement desensitization and reprocessing (EMDR) was derived from an accidental discovery by the North American psychologist Francine Shapiro in 1989: she found that spontaneous saccadic eye movements could magically lead to the reduction of distress brought by her disturbing memories (8). Nowadays, saccadic eye movements have developed into a standardized psychotherapy, containing patient history, preparation, assessment, desensitization, installation, body scan, closure, and re-evaluation. According to the Adaptive Information Processing (AIP) model, traumatic experience that cannot be fully processed will be stored in individuals' memory network in a frozen state (9). Such dysfunctional stored memories will enhance the chance of suffering from mental disorders (10, 11). While conducting eye movements during negative memories recall, the reprocessing of negative experience is facilitated, which leads to the relief of suffering.
EMDR was first employed in the treatment of post-traumatic stress disorder (PTSD). Two studies in 1989 demonstrated that saccadic eye movements could reduce frequency of traumatic memories and PTSD symptoms (8, 12). Over the past 30 years, EMDR has been considered as the first-line treatment of PTSD. Recently, studies revealed that EMDR can also be utilized in treating mental disorders that closely associated with distressing life experiences (13, 14). It is well-known that childhood trauma and stressful life events commonly present in MDD patients. According to a survey, about 55% of patients with MDD reported at least one type of childhood trauma (15). Besides, stressful life events are defined as a vital risk factor in the development and maintenance of MDD (16, 17). The presence of distressing life experiences in people with MDD may even prolong the disease course (18). In light of the close relationship between MDD and adverse events, researchers have started to apply EMDR in treating MDD (19–26).
Although there were reviews on the effectiveness of EMDR for MDD and affective disorders (13, 27–29), these reviews did not implement strict inclusion criteria, and some of the included studies were non-controlled trials, which may undermine the persuasiveness of research results. Besides, some reviews included studies on both adults and adolescents with MDD. The heterogeneity of study subjects may lower the reliability of review outcome. Therefore, the purpose of this study is to conduct a meta-analysis based on exhausted inclusion criteria and further determine the effectiveness of EMDR in the treatment of adults with MDD based only on RCTs.
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Discussion
Eight randomized controlled trials were included in this meta-analysis of EMDR efficacy for adults with MDD. First, we conducted a comparison between EMDR and “No Intervention.” Our study revealed that EMDR was more effective in reducing depressive symptom than “No Intervention.” Second, we compared EMDR with CBT. The Primary and exploratory outcomes manifested that EMDR outperformed CBT in reducing depressive symptoms and enhancing remission. The subgroup analysis showed that there were no significant differences between sessions ≤ 6 and sessions >6.
The results of our study demonstrated that EMDR was superior to “No Intervention” in reducing depressive symptoms. Besides, three studies found that EMDR outperformed co-intervention control group in improving remission, but the differences between EMDR and the co-intervention control group failed to reach statistical significance. Currently EMDR is utilized to treat aversive memories and associated negative feeling and cognition. Of the included studies in this meta-analysis, about a half of MDD participants reported that they suffered from early or recent environmental exposures (19, 21, 23, 26). This may imply that EMDR can be used to treat this cohort.
The discussion about the mechanism of EMDR treatment has been around for a long time. The working-memory account is one of the accounts used to explain the role of eye movements in EMDR treatment. It posits that whenever patients recall past events, they will consume the processing resources of working memory at the same time. While performing eye movements during recall of negative memories, the processing resources are used up (39, 40). By occupying the expected processing resources of aversive memories, eye movements attenuate the vividness and emotionality of these negative memories. Because such memories appeared in a weakened form, patients will find that memories are not as horrible as they used to think, which means that the negative impact of past events also reduced accordingly (41).
Our findings suggested that EMDR was more effective than CBT in treating depressive symptoms and improving remission. To the best of our knowledge, this is the first meta-analysis to compare the efficacy of EMDR and CBT in the treatment of MDD in terms of symptom reduction and remission. The treatment target of EMDR is disturbing memories. Despite the fact that CBT also considers the impact of disturbing memories, it emphasizes the importance in shifting dysfunctional beliefs (42). Different treatment targets of these two psychological therapies may indicate that they are applicable in different clinical specific populations. In the trials that compared EMDR with CBT in our study, almost all of the participants reported stressful or traumatic experience, which implies that they may benefit more from trauma-focused psychotherapy like EMDR. Such psychotherapy can effectively deal with the influence of negative past events, which is a vital factor in the maintenance of current symptoms. Although EMDR and TF-CBT both belong to trauma-focused psychotherapy, one of the included trials reported an advantage for EMDR over another (23). The possible explanation may be the homework assignment, which is an essential component of CBT (43, 44). Compared with MDD patients without traumatic experience, those who underwent adverse events tended to report more severe symptoms (18), which may reduce their motivation to finish homework. The low compliance with homework completion may slow down the onset time of TF-CBT. In contrast, the efficacy and onset time of EMDR do not depend on homework assignment (9). Such characteristic may indicate that even if patients do not finish homework, the time required for EMDR to take effect will not be greatly affected. Hence, EMDR may work faster than TF-CBT for MDD patients in a given time, especially for those with severe symptoms.
We also conducted a subgroup analysis to investigate the effect of EMDR based on number of therapy sessions. However, we didn't find any significant difference. The finding of number of therapy sessions was consistent with the findings in patients with other mental disorders (14, 45, 46). The minimal number of therapy sessions in our study was one session (22), while the maximum number was 24, targeting treatment-resistant depression patients (23). Our result may imply that the efficacy of EMDR will not be restricted by therapy sessions because only the most distressing part of the incident, rather than the whole traumatic event, will be included as the treatment target during the treatment of EMDR (8, 9). The impact of the most distressing part is effectively dealt with in a short period of time. Hence, such targeted therapy makes it possible to relieve patients' symptoms even in a single session. Nevertheless, for those with severe symptoms, more treatment sessions are still necessary.
The aforementioned findings are consistent with the meta-analysis published earlier (27) and further confirm the effectiveness of EMDR on adult MDD patients. However, there are also several differences between the present meta-analysis and the one published before. The present meta-analysis included only RCT and applied strict inclusion criteria. RCT and strict inclusion criteria can provide plausible and strong evidence for the effectiveness of EMDR. Moreover, the present meta-analysis focused only on the adult cohort. The high homogeneity of study subjects makes our results more reliable and helps to promote the use of EDMR in adults with MDD. Last but not the least, besides studies conducted in western countries, the present study also included studies conducted in China, which indicates that the effectiveness of EMDR may not be influenced by the cultural background of patients.
There are several limitations in this meta-analysis. First, the number of included trials in this meta-analysis was small and the trials were rated as high risk of bias. It is recommended to conduct large well-designed RCTs to estimate the efficacy of EMDR in the future. Second, we did not have enough data to conduct subgroup analyses of anxiety symptoms and level of functioning. Only three trails reported the improvement of anxiety symptoms, and one trail provided information on level of functioning. Residual anxious and functional symptoms also play an important role in the recovery of adult MDD patients. Future studies are recommended to include anxiety symptoms and level of functioning as secondary outcomes in the investigation of the efficacy of EMDR in adult MDD patients. Third, the definition and measurement of remission in our studies were various, which may limit the comparability of the finding concerning remission assessed in other studies. A standardized semi-structure interview conducted by clinicians to identify remission is necessary in future studies.
Conclusion
In general, notwithstanding the limitations of this meta-analysis, our study further confirmed the efficacy of EMDR in treating adults with MDD. We conducted two comparisons: (1) EMDR vs. “No Intervention” and (2) EMDR vs. CBT. Our findings suggested that EMDR was more effective in reducing depressive symptoms in comparison with “No Intervention” and CBT. Considering that most of the adult MDD patients had suffered from adverse experience, these findings may imply that EMDR has the potential to be an evidenced-based treatment for adults with depression, especially those with negative life events. However, these results should be considered cautiously due to the small sample size and methodological flaws. Further studies with high-quality design and large samples are needed to explore the efficacy of EMDR in treating adults with MDD and its long-term effects. Furthermore, including anxiety symptoms and level of functioning as secondary outcomes in the investigation of the efficacy of EMDR is also recommended in the future.