Symptom predictors of response to electroconvulsive therapy in older patients with treatment-resistant depression

Background: Electroconvulsive therapy (ECT) has been used for treatment-resistant depression. However, predictors of response to ECT have not been adequately studied using the Montgomery and Asberg Depression Rating Scale, especially in older patients with treatment-resistant depression. Methods: This study included 18 Japanese patients who fulfilled the Diagnostic and Statistical Manual of Mental Disorders Fourth Edition Text Revision criteria for a diagnosis of major depressive disorder or bipolar disorder with a current major depressive episode, and met the definition of treatment-resistant depression outlined by Thase and Rush, scoring >= 21 on the Montgomery and Asberg Depression Rating Scale. The three-factor model of the Montgomery and Asberg Depression Rating Scale was used for analysis. Factor 1 was defined by three items, factor 2 by four items, and factor 3 by three items, representing dysphoria, retardation, and vegetative symptoms, respectively. ECT was performed twice a week for a total of six sessions using a Thymatron System IV device with the brief pulse technique. Clinical responses were defined on the basis of a >= 50% decrease in total pretreatment Montgomery and Asberg Depression Rating Scale scores. Results: The mean pretreatment factor 2 score for responders (n = 7) was significantly lower than that for nonresponders (n = 11). Furthermore, a significant difference in mean factor 3 score between responders and nonresponders was observed one week after six sessions of ECT, indicating a time lag of response. No significant differences were observed for age, number of previous episodes, and duration of the current episode between responders and nonresponders. Conclusion: This study suggests that a low pretreatment factor 2 score is a good predictor of response to ECT in older patients with major depression.