Diverging Trajectories of Depressive Symptoms During Electroconvulsive Therapy: Toward Personalized Treatment.

Background: While electroconvulsive therapy (ECT) is an effective treatment for depression, patient responses vary. In addition, there is a lack of guidance in making treatment decisions for patients with an initial nonresponsive trajectory. In this study, we aimed to identify distinct latent patient trajectories and explore outcomes among patients who had not responded after 9 treatments but who continued therapy. Methods: In this register-based cohort study, including 344 patients (61% female), we applied a latent class mixed model to identify latent patient trajectories and investigated variables associated with class affiliation in a multinomial regression analysis. We also identified nonresponders at treatment 9 and investigated final outcomes in a logistic regression model. Results: Three latent classes were identified, all of which showed improvement, although classes 2 and 3 showed faster and steeper symptom reduction, with mean Montgomery-Åsberg Depression Rating Scale (MADRS) scores post-ECT of 9.8 and 5.3, respectively. Class 1 showed a shallower response pattern, with a mean MADRS score post-ECT of 20.9; variables associated with affiliation to this class were longer duration of depressive episode, nonpsychotic depression, lower age, and lower baseline depression level. Of nonresponders to ECT at session 9, 44.9% achieved final response and 17.9% achieved remission; female sex and lower age groups (<60) were associated with higher odds of final nonresponse. Conclusions: Our study supports ECT as an effective treatment for depression, while highlighting the existence of distinct response trajectories. A significant proportion of patients with an initial nonresponse trajectory may still benefit from continued ECT. Our findings reinforce the importance of individualized treatment decisions guided by clinical response and close monitoring.