Effects of dose on early treatment response to bifrontal electroconvulsive therapy in Schizophrenia: A retrospective study

Abstract

Schizophrenia is the leading indication for electroconvulsive therapy (ECT) in Asia; however, optimal ECT parameters for this condition remain under-researched. This study examines the impact of stimulus dosage in bifrontal ECT on symptomatic improvement in 122 patients treated at the Institute of Mental Health, Singapore.

In this retrospective analysis, patients were categorized into two groups based on a 1.5 × seizure threshold (DRST) cutoff: a standard dosage group (≤1.5 × DRST) and a high dosage group (>1.5 × DRST). Paired t-tests were used to assess changes in clinical scores—positive psychotic symptoms, quality of life, and cognition—after six ECT sessions. Generalized linear models evaluated associations between dosage groups and symptomatic changes.

Both groups showed significant improvements in positive psychotic symptoms, as measured by the Brief Psychiatric Rating Scale (BPRS) positive psychotic symptom subscale (p < 0.001), and in quality of life (Q-LES-Q-SF and EQ-5D utility scores; p < 0.03 for the high-dose group, p = 0.006 for the standard-dose group). Only the standard dosage group demonstrated significant cognitive improvement (MoCA, p = 0.04), while the high-dose group did not. Notably, the high-dose group experienced greater reductions in positive psychotic symptom scores (p = 0.004) and greater improvements in quality of life (p = 0.002) compared to the standard-dose group. However, linear regression analysis found no significant between-group differences in post-treatment MoCA scores.

These findings suggest that higher suprathreshold dosages of bifrontal ECT may accelerate improvement in positive psychotic symptoms in schizophrenia, highlighting the need for further research to optimize ECT protocols and treatment outcomes.