Predictors of Response to Electroconvulsive Therapy Obtained Using the Three-Factor Structure of the Montgomery and Asberg Depression Rating Scale for Treatment-Resistant Depressed Patients

Objective: Electroconvulsive therapy (ECT) is one of the most effective treatments for refractory major depressive disorder (MDD). Although studies have examined different predictors of a positive response to ECT, predictors based on symptoms listed on a depression rating scale have not been studied. Methods: This study included 24 Japanese patients who fulfilled the Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition criteria for MDD or bipolar disorder with current major depressive episode. All subjects had a score of 21 or higher on the Montgomery and Asberg Depression Rating Scale (MADRS). The 3-factor model of MADRS was used for analysis: factor 1 (dysphoria) was defined by 3 items, factor 2 (retardation) was defined by 4 items, and factor 3 (vegetative symptoms) was defined by 3 items. Electroconvulsive therapy was performed 2 times a week for a total of 6 sessions using the Thymatron System IV device (Somatics, Inc., Lake Bluff, Ill) with the brief-pulse technique. A clinical response was defined as a 50% or greater decrease on the pretreatment total MADRS score. Results: The mean factor 1 score of responders (n = 17) at pretreatment was significantly higher than that of the nonresponders (n = 7). Furthermore, a significant difference in mean factor 3 scores between responders and nonresponders was observed 1 week after the 6 ECT sessions were complete, indicating a lag in response time. No significant differences were observed in age, number of previous episodes, and duration of current episodes between the responders and nonresponders. Conclusions: This study suggests that a high factor 1 MADRS score at pretreatment was a good predictor of response to ECT in patients with treatment-resistant MDD.