Comparative efficacy and cognitive safety of bifrontal versus bitemporal electroconvulsive therapy in adolescents with major depressive disorder: a retrospective cohort study.

Background: Electroconvulsive therapy (ECT) remains a rapid and highly effective treatment for severe, treatment-resistant depression in adolescents, particularly when immediate suicide risk is present. However, its clinical utilization in the pediatric population is still low, largely restricted by pervasive concerns regarding cognitive impairment. While randomized trials in adults suggest that bifrontal (BF) electrode placement offers a superior cognitive safety profile compared to the standard bitemporal (BT) placement, comparative evidence specifically regarding the developing adolescent brain remains scarce. Methods: We conducted a retrospective cohort study at the Department of Psychiatry in a tertiary general hospital, analyzing 217 adolescents (aged 12-18 years) diagnosed with major depressive disorder (MDD) who underwent a course of ECT between January 2018 and June 2024. Patients were categorized into the BF group (n = 111) or BT group (n = 106) based on the electrode placement utilized. The primary efficacy outcomes were the response rate (≥50% reduction in 24-item Hamilton Depression Rating Scale (HAMD-24) scores) and remission rate (HAMD-24 score ≤8). Secondary outcomes included the reduction in suicidal ideation (Beck Scale for Suicide Ideation (BSSI) scores), the incidence of subjective memory complaints, and post-ictal recovery time. Multivariate logistic regression was performed to identify independent predictors of subjective memory complaints, adjusting for baseline severity and concurrent medications. Results: Baseline demographic and clinical characteristics, including severity of depression and suicidality, were well-balanced between groups. The BF group achieved a numerically higher response rate (85.6%) compared to the BT group (82.1%), although this difference did not reach statistical significance (p = 0.478; odds ratio [OR] = 1.29, 95% CI 0.64-2.42). Remission rates were also comparable (33.3% vs. 33.0%; p = 0.963). Both groups showed equal efficacy in reducing suicidal ideation (p > 0.05). While efficacy outcomes were similar, the two modalities showed notable differences in two specific safety-related endpoints that are relevant to daily clinical practice: the incidence of subjectively reported memory complaints (28.8% in the BF group compared with 67.9% in the BT group; p < 0.001; OR = 0.20, 95% CI 0.11-0.36) and the objectively measured post-ictal recovery time (23.7 ± 7.7 min for BF compared with 33.4 ± 9.9 min for BT; p < 0.001; Cohen's d = 1.12). After adjusting for age, baseline HAMD-24 scores, and concurrent use of benzodiazepines and antipsychotics, BF placement remained a significant independent protective factor against subjective memory complaints (adjusted OR = 0.21, 95% CI: 0.11-0.39, p < 0.001). Conclusion: In adolescents with MDD, bifrontal ECT showed short-term antidepressant and anti-suicidal outcomes comparable to those of bitemporal ECT in this retrospective cohort. BF ECT appeared to be associated with fewer subjective memory complaints (as assessed by spontaneous patient reports and daily physician inquiries) and shorter post-ictal recovery time. These two endpoints, while clinically relevant in routine practice, do not capture the full spectrum of cognitive function; standardized neuropsychological assessment would be required for a comprehensive comparison. Given the retrospective design and non-random treatment allocation, these findings should be interpreted cautiously and confirmed in prospective controlled studies.